|Year : 2021 | Volume
| Issue : 2 | Page : 134-138
Challenges of COVID-19 vaccination in the context of transplantation - A narrative review
Hari Shankar Meshram1, Vivek B Kute1, Sanjay K Agarwal2, Manisha Sahay3
1 Department of Nephrology, Institute of Kidney Diseases and Research Center and Dr. H L Trivedi Institute of Transplantation Sciences, Ahmedabad, Gujarat, India
2 Department of Nephrology, All India Institute of Medical Sciences, New Delhi, India
3 Department of Nephrology, Osmania General Hospital, Hyderabad, Telangana, India
|Date of Submission||20-May-2021|
|Date of Decision||30-May-2021|
|Date of Acceptance||06-Jun-2021|
|Date of Web Publication||30-Jun-2021|
Prof. Vivek B Kute
Department of Nephrology and Transplantation, Institute of Kidney Diseases and Research Center and Dr. H L Trivedi Institute of Transplantation Sciences, Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
Coronavirus disease 19 (COVID-19) vaccination is imperative for preventing disease transmission and combating the associated mortality. Vaccination in the setting of transplantation is a complex issue. Owing to the chronic immunocompromised state in a transplant recipient, the immunogenicity of the vaccines is expected to be attenuated. Immunizing pretransplant patients will also be a challenge, as chronic kidney disease is also an immunocompromised state causing a lower seroconversion rate. The protective immune response generated is also expected to fade earlier. Enumerable psychosocial barriers exist regarding vaccine acceptance and a tender bond between health care providers and patients is essential for the smooth conduct of the vaccination program. The tolerability and safety profile of different available vaccines are reassuring in the general population but more data are needed in transplant communities. In addition, the efficacy data of COVID-19 vaccines are derived from the general population and preliminary reports in transplant patients have shown weakened immune response to vaccination. As of May 2021, Indian government advisories have approved three vaccines: COVIDSHIELD, COVAXIN, and Sputnik. Hence, research on vaccine efficacy with different vaccine constituents, dosing, and intervals is necessary for an effective protocol for vaccination in transplantation.
Keywords: Coronavirus disease 19 vaccine, immunogenicity, organ transplantation, waitlisting
|How to cite this article:|
Meshram HS, Kute VB, Agarwal SK, Sahay M. Challenges of COVID-19 vaccination in the context of transplantation - A narrative review. Indian J Transplant 2021;15:134-8
|How to cite this URL:|
Meshram HS, Kute VB, Agarwal SK, Sahay M. Challenges of COVID-19 vaccination in the context of transplantation - A narrative review. Indian J Transplant [serial online] 2021 [cited 2021 Jul 24];15:134-8. Available from: https://www.ijtonline.in/text.asp?2021/15/2/134/319889
| Introduction|| |
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection causing the ongoing pandemic Coronavirus disease 19 (COVID-19) has become one of the most dramatic global health emergencies, the world has ever witnessed. The health authorities are still battling for a definitive therapy for COVID-19 and encouraging results of the vaccines in last few months have emerged bringing new hope. Currently, India is witnessing the highest number of COVID-19 cases in the world. As of April 26, 2021, a total of 14, 19, 11, 223 vaccinations have been done as reported by the Ministry of health and family welfare, India (MOHFW). India has a predominant living donor kidney transplant program. A total of 61,821 organ transplants have been performed between 2013 and 2019, including 48,083 kidney (living donor = 41,197, deceased donor = 6886), 11,971 liver (living donor = 8405, deceased donor = 3566), 1082 heart, 573 lung, 100 pancreas and 8 small bowel transplants as per Global Observatory on Donation and Transplantation data 2013–2019. Transplantation activities in the nation remained at halt during the pandemic and restoration of transplantation activities requires a stepped and staged approach in which vaccination is going to play a key role. The SARS-Cov2 infection has drastically impacted the transplant communities, with high morbidity and mortality in transplant recipients., The waitlisted patients are at higher risk for COVID-19 associated mortality. In the middle of the COVID-19 crisis akin to the national health emergency, an effective vaccine in COVID-19 management armamentarium is a real need, and the transplant subgroup has to be dealt with further precautions for vaccine-associated safety and efficacy. The combination of getting vaccinated and following the Government's recommendations on key COVID appropriate behaviors at all times, before, during, and after vaccination can only offer the best protection from COVID-19 in transplant recipients. Here, we discuss the challenges of COVID-19 vaccination in transplant recipients in the Indian context and hope that this information may be useful for other developing countries for COVID-19 vaccination in their transplant programs.
Combating hesitancy to coronavirus disease 19 vaccine
The issue of awareness and attitude for the COVID-19 vaccine is an important issue worldwide., In addition, the acceptance of vaccines in masses could change with different geography and socio-economic status. Murphy et al., in a survey assessing psychological characteristics associated with the COVID-19 vaccine, found around 30% hesitancy in the United Kingdom and Ireland's residents. Lazarus et al. conducted a global survey and reported around 71.5% acceptance rate of vaccination, with respondents from China showing the highest positive response and those from Russia showing the highest negative response. Unarguably, in India and many other nations also, there is some hesitancy for the COVID-19 vaccine among both health care professionals and the common man. Around one-third health-care workers preferred to wait despite having vaccine access in 100 random health-care workers in our center (unpublished data). Furthermore, there is a lack of awareness predominantly in rural areas. The most challenging aspect is gaining faith for vaccination in current times where efficacy and safety are not adequately known in transplant recipients. The ways to increase awareness and overcome hesitancy would be utilizing the strategy of information education communication for promoting vaccination amongst transplant recipients, using virtual platforms for COVID-19 vaccine introduction, and education for all transplant team members who will be a major source of information for the transplant recipients. The message should be delivered clearly and concisely to the transplant candidates and recipients that they are theoretically less likely to develop a robust immune response compared to the general population, still, at the time of the pandemic, some degree of immunity is better than no immunity and so vaccination is important. None of the currently approved COVID-19 vaccines contain live virus and these vaccines carry no risk of causing COVID-19 infection. The benefits of vaccination far overweigh any unproven risks.
Accessibility to the vaccine
Increasing age is now recognized as the most important risk factor for the severity of COVID-19. The median age of transplant patients with COVID-19 in large Indian studies is below 45 years. In the initial stages, the vaccine was available for health workers, so transplant recipients had to wait for their priority. As of April 2021, the Indian guidelines include COVID-19 vaccine beneficiaries with age above 60 and age 45–60 years with co-morbidities. The majority of the Indian transplant candidates and recipients are below 45, hence are getting exempted from the vaccine. From May 2021, the government has made vaccine available for the age group above 18 years and hence, the bulk of the transplant recipients will be covered. The place of vaccine administration has expanded from few centers to many dedicated COVID-19 centers in all remote places. There will always be a potential for a gap between supply, demand, and access to COVID 19 vaccine. The gap can be filled by making the whole process as a continuous process and by designating quality check personnel at each level to maintain synergy in all aspects of vaccination. Merging regular follow-up visits with vaccination, rather than scheduling for vaccination at a separate visit, is a good alternative to ensure smooth vaccination strategy. In India, the government has authorized three vaccines COVIDSHIELD, COVAXIN, and Sputnik. Other foreign vaccines like Moderna, or Pfizer are yet to be licensed and be made available in India. The transplant recipients from high-income subgroups might want to wait for the vaccine with better efficacy and henceforth would not volunteer for current government-approved vaccine owing to lack of data on safety and efficacy in transplant recipients. This problem can be solved by approving all vaccines with published efficacy data in the country so that individual has all options available.
| Vaccination in Paediatric Transplant Recipients|| |
The COVID-19 vaccine currently is not approved for use in children due to the lack of safety data in this population as on today. Pfizer vaccine has received approval for pediatric vaccination; however, it is not currently available in India. Almost 10% of transplanted recipients in India are of the pediatric age group and are excluded from vaccination. Merging COVID-19 vaccination as part of national immunization program will be difficult but should be done as early as possible once the vaccine is approved for children.
| Infrastructure and Manpower to Increase Vaccine Access|| |
Undoubtedly, immunizing this enormous group will take time. Cold chain infrastructure remained a problem for past vaccinations in the developing world, and the armoury is not enough even for current vaccination practices. Repairing, rebooting existing cold chains and manufacturing new ones at all levels should be the priority for fruitful results. Temperature-sensitive color coding for the COVID-19 vaccine-like what is done for oral polio vaccine may ensure cold chain maintenance. There is overloading of nursing services, and so for immunizing such a big population, intensifying nursing training and other personnel should be done for administering the vaccine. To fulfill the job of reaching world's second-largest population, we should create more vaccination centers, and local vaccinators. Temporary diverging private and public sector hospitals as vaccination centers would be helpful. In India, previously low financial remuneration to local vaccinators led to low vaccination rates, hence a reasonable pay to local vaccinators for door-to-door vaccination could yield fascinating results.
Effectiveness of coronavirus disease 19 vaccines in transplant communities
COVID-19 vaccine trials have shown encouraging results worldwide. The COVE study investigating mRNA-1273 SARS-CoV-2 showed 94% efficacy in the general population with no serious side effect profile. The C4591001 Clinical Trial Group showed 95% efficacy and no safety issues with the BNT162b2 vaccine. Dagan et al., in a nationwide study, showed the BNT162b2 vaccine to be effective in reducing COVID-19-related mortality by 72% after the first dose. They also cautioned the variability in efficacy among individuals with comorbid conditions. Voysey et al. showed 64% efficacy of ChAdOx1 nCov-19 vaccine in a UK cohort. Sadoff et al. demonstrated the safety and tolerability of Ad26. CoV2 vaccine., The overall impact of the vaccine on different strains is gloomy, though a study by Madhi et al. showed good efficacy of the ChAdOx1 nCov-19 vaccine against the B. 1.351 variant. Logunov et al. reported 91.6% efficacy of Sputnik vaccine in a Russian cohort with acceptable tolerability. Unfortunately, all these trials, based on which COVID-19 vaccines were approved, excluded solid organ transplant recipients. Hence, efficacy in this group of patients is unknown. Vaccine efficacy and safety is expected to vary as per ethnicity and race, and hence there is an urgent need for a comprehensive analysis of the efficacy of the different vaccines in waitlisted and organ transplants worldwide including India. We might be potentially requiring modified vaccination strategies which may include different dosing and alternative schedules. There are a few studies reporting vaccination efficacy in transplant communities. A recent report by Husain et al. showed only 25% of transplant patients with antibody response after full dose of vaccination. Benotmane et al., showed weakened antibody response of 11% among transplant recipients following the first dose of the mRNA vaccine. In preliminary reports, Boyarsky et al. showed reduced anti-spike protein antibodies with messenger RNA Vaccine compared to the general population., Ou et al., recently investigated the first-ever comprehensive data regarding safety and immunogenicity with BNT162b2 and mRNA-1273 COVID-19 vaccine, and found reassuring results compared to the general population. Recently, there are also breakthrough COVID-19 cases following COVID-19 vaccination which is a matter of concern., Still, at this point, it is crucial to research for the ideal vaccine for different ethnicity, race and degree and type of immunosuppression regimens. Due to the chronic immunosuppressed state in organ transplant patients, the immunogenicity and the duration of antibody protection are expected to be suboptimal. The value and implications of any changes in immunosuppression regimen considering the timing of vaccination remain uncertain, and modifying maintenance immunosuppression to enhance vaccine responsiveness cannot be recommended empirically without high-level evidence as the risk of graft dysfunction always exists. Consequently, the patients are advised to take utmost precautions like hand hygiene and social distancing, till we have any definitive vaccines available for COVID-19.
The Indian guidelines suggest deferring transplant for 2 weeks after vaccination and 1–6 months after transplant. Vaccinating pretransplant candidates is also an area of research as the waitlisted and chronically dialysed patient are unlikely to elicit a proper antibody response and even the durability of the vaccine response will be questionable. Biliary et al, showed 80% dialysis patients respond to vaccine. Labriola et al. showed that the seroresponse to COVID-19 faded substantially in a dialysis cohort. Recent data have shown mixed results regarding the immunogenicity of the vaccine in dialysis and transplant patients. Whether any particular type of vaccine would prove better in hemodialysis patients? This needs to be further elucidated. Moreover, the timing and schedule of vaccination in this population will be a matter of further research. Immunosuppression may alter the immune response to the vaccine, and hence, the perfect timing of vaccine after immunosuppression will be debated. The data have shown a balanced humoral and T-cell immune response for messenger RNA vaccine and subunit vaccine which are lacking in the inactivated vaccine. Any live vaccine is contraindicated in a transplant patient, and so it will be the norm with COVID-19 vaccine as well. However, long-term studies will further clear our knowledge of vaccination in transplant patients of Indian origin. Also of great importance is to emphasize that the family members of the transplant recipients should also get vaccinated.
| Fear of Postvaccination Complications|| |
Previously, reports of anti-HLA antibodies concerned the transplant communities after administration of the H1N1 pandemic adjuvant vaccine. However, studies supported that the antibodies generated through vaccines were not donor specific. ChAdOx1 nCov-19 has been shown to be associated with thrombotic thrombocytopenia, and whether there would be any hematological complications in pre-transplant and post-transplant patients of Indian origin is yet to be determined. Fear of potential adverse events following vaccination (AEFI) against COVID-19 will be responsible for vaccine hesitancy. There is a potential risk for both clinical and subclinical immune injury after vaccination in transplants but no data is available in transplant recipients. The issue can be solved by cautiously choosing the pilot group with low immunological profile and vigorous surveillance for them. The vaccination can be extended further to all transplants if the pilot group has no adverse effects. An effective tracking system needs to be developed to compare the efficacy and safety of different vaccines. A detailed investigation of major AEFI and timely reporting should be done, through digital centralized format. Communication strategies between transplant patients and transplant centers through telemedicine, boomed in the management of COVID-19 patients and can also mitigate any possibility of AEFI, in vaccinated patients.
| Optimal Timing for the 2nd Dose of Coronavirus Disease 19 Vaccine|| |
In light of a recent report about the efficacy of single-dose and timing of the second dose of Oxford vaccine, the Indian government has extended the second dose duration to an interval of 12–16 weeks. Data from the clinical trials conducted by Oxford and AstraZeneca in the UK showed that the vaccine had only around 54% efficacy if administered at 4 weeks as compared to 79% efficacy if the gap is extended to 12 weeks. In case, a candidate becomes COVID-19 positive following the first dose, then the second dose is deferred for 3 months. If a patient was treated with monoclonal antibodies or convalescent plasma for COVID-19 infection, he/she should wait at least 90 days before getting vaccinated. The effectiveness of vaccines in trials cannot be truly generalized and implemented in real-world situations with ongoing COVID-19 surge.
CDC recently changed recommendations for vaccinated individuals to allow them to spend time together in small groups. However, probably this does not apply to people at high risk of COVID infection, which includes transplant patients and those on immune-suppressing medications. Transplant recipients should continue to observe safe practices.
Planning for future
There are only speculations about the sub-optimal COVID-19 antibody response after vaccination in immunosuppressed recipients and only future will unfold the protective antibody levels in them. How often they would be requiring booster is another question to ponder upon. In past other flu epidemics, there was a problem with changing viral strains. The variants circulating in India and their impact are gloomy. Still, the most recognized and concerned variants in India are a double mutant B.1.617 variant, UK Variant (B.1.1.7); South African variant (B.1.351), and Brazilian variant (P. 1). Hence, epidemiologic surveillance and genomic profiling for COVID-19 strain need to be done regularly, especially in areas where COVID-19 incidence is high and there is a massive second wave/surge of COVID-19. In a vast and developing country like India, it would be tough to convince and ensure regular follow-up for vaccination. Additional studies in future will be needed for shifting to once dosing or oral vaccines if possible. An intranasal vaccine developed by Bharat biotech is planned to be approved in the latter half of the year, which has the potential to surpass the barrier of injectables. Moreover, the immune response generated by the intranasal routine is expected to be diverse and more robust. The studies evaluating the safety and efficacy of the intranasal vaccine in transplant will be further needed.
| Conclusion|| |
COVID-19 vaccine has shown excellent results in the general population through studies showing its utility in transplant communities are scarce. This has been a hot topic and dedicated research exploring the safety and efficacy of the vaccine is mandated. In current practices, a harmonious relationship between patients and transplant physicians is the key element to outline a balanced discussion of the benefits, risks, and potential hazards regarding COVID-19 vaccination.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Kute VB, Bhalla AK, Guleria S, Ray DS, Bahadur MM, Shingare A, et al
. Clinical profile and outcome of COVID-19 in 250 kidney transplant recipients: A multicenter cohort study from India. Transplantation 2021;105:851-60.
Khairallah P, Aggarwal N, Awan AA, Vangala C, Airy M, Pan JS, et al.
The impact of COVID-19 on kidney transplantation and the kidney transplant recipient – One year into the pandemic. Transplant Int 2021;34:612-21.
De Meester J, De Bacquer D, Naesens M, Meijers B, Couttenye MM, De Vriese AS, et al
. Incidence, characteristics, and outcome of COVID-19 in adults on kidney replacement therapy: A regionwide registry study. J Am Soc Nephrol 2021;32:385-96.
Kute V, Agarwal SK, Prakash J, Guleria S, Shroff S, Sharma A, et al
. NOTTO COVID-19 vaccine guidelines for transplant recipients. Indian J Transplant 2021;15:1-3. [Full text]
Fisher KA, Bloomstone SJ, Walder J, Crawford S, Fouayzi H, Mazor KM. Attitudes toward a potential SARS-CoV-2 vaccine: A survey of U.S. adults. Ann Intern Med 2020;173:964-73.
Largent EA, Persad G, Sangenito S, Glickman A, Boyle C, Emanuel EJ. US public attitudes toward COVID-19 vaccine mandates. JAMA Netw Open 2020;3:e2033324.
Malik AA, McFadden SM, Elharake J, Omer SB. Determinants of COVID-19 vaccine acceptance in the US. EClinicalMedicine 2020;26:100495.
Murphy J, Vallières F, Bentall RP, Shevlin M, McBride O, Hartman TK, et al
. Psychological characteristics associated with COVID-19 vaccine hesitancy and resistance in Ireland and the United Kingdom. Nat Commun 2021;12:29.
Lazarus JV, Ratzan SC, Palayew A, Gostin LO, Larson HJ, Rabin K, et al
. A global survey of potential acceptance of a COVID-19 vaccine. Nat Med 2021;27:225-8.
Sur D. Challenges in new vaccine introduction in a national program in India. Indian J Public Health 2016;60:171-5.
] [Full text]
Ashok A, Brison M, LeTallec Y. Improving cold chain systems: Challenges and solutions. Vaccine 2017;35:2217-23.
Lahariya C. A brief history of vaccines and vaccination in India. Indian J Med Res 2014;139:491-511.
] [Full text]
Baden LR, El Sahly HM, Essink B, Kotloff K, Frey S, Novak R, et al
. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med 2021;384:403-16.
Polack FP, Thomas SJ, Kitchin N, Absalon J, Gurtman A, Lockhart S, et al
. Safety and efficacy of the BNT162b2 mRNA COVID-19 vaccine. N Engl J Med 2020;383:2603-15.
Dagan N, Barda N, Kepten E, Miron O, Perchik S, Katz MA, et al
. BNT162b2 mRNA COVID-19 vaccine in a nationwide mass vaccination setting. N Engl J Med 2021;384:1412-23.
Voysey M, Clemens SAC, Madhi SA, Weckx LY, Folegatti PM, Aley PK, et al
. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: An interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. Lancet 2021;397:99-111.
Sadoff J, Le Gars M, Shukarev G, Heerwegh D, Truyers C, de Groot AM. Safety and immunogenicity of the Ad26. COV2. S COVID-19 vaccine candidate: Interim results of a phase 1/2a, double-blind, randomized, placebo-controlled trial. MedRxiv 2020. doi: https://doi.org/10.1101/2020.09.23.20199604
Sadoff J, Le Gars M, Shukarev G, Heerwegh D, Truyers C, de Groot AM, et al
. Interim results of a phase 1–2a Trial of Ad26. COV2. S COVID-19 vaccine. N Engl J Med 2021;384:1824-35.
Madhi SA, Baillie V, Cutland CL, Voysey M, Koen AL, Fairlie L, et al
. Efficacy of the ChAdOx1 nCoV-19 COVID-19 vaccine against the B. 1.351 variant. N Engl J Med 2021;384:1885-98.
Logunov DY, Dolzhikova IV, Shcheblyakov DV, Tukhvatulin AI, Zubkova OV, Dzharullaeva AS, et al
. Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: An interim analysis of a randomised controlled phase 3 trial in Russia. Lancet 2021;397:671-81.
Kates OS, Haydel BM, Florman SS, Rana MM, Chaudhry ZS, Ramesh MS, et al
. COVID-19 in solid organ transplant: A multi-center cohort study. Clin Infect Dis 2020 Aug 7;ciaa1097. doi: 10.1093/cid/ciaa1097. Online ahead of print.
Glenn DA, Hegde A, Kotzen E, Walter EB, Kshirsagar AV, Falk R, et al
. Systematic review of safety and efficacy of COVID-19 vaccines in patients with kidney disease. Kidney Int Rep 2021;6:1407-10.
Husain SA, Tsapepas D, Paget KF, Chang JH, Crew RJ, Dube GK, et al
. Postvaccine Anti-SARS-CoV-2 spike protein antibody development in kidney transplant recipients. Kidney Int Rep 2021;6:1699-700.
Benotmane I, Gautier-Vargas G, Cognard N, Olagne J, Heibel F, Braun-Parvez L, et al
. Weak anti-SARS-CoV-2 antibody response after the first injection of an mRNA COVID-19 vaccine in kidney transplant recipients. Kidney Int 2021;99:1487-9.
Boyarsky BJ, Werbel WA, Avery RK, Tobian AA, Massie AB, Segev DL, et al
. Immunogenicity of a single dose of SARS-CoV-2 messenger RNA vaccine in solid organ transplant recipients. JAMA 2021;325:1784-6.
Boyarsky BJ, Werbel WA, Avery RK, Tobian AA, Massie AB, Segev DL, et al
. Antibody response to 2-dose SARS-CoV-2 mRNA vaccine series in solid organ transplant recipients. JAMA 2021;325:2204-6.
Ou MT, Boyarsky BJ, Motter JD, Greenberg RS, Teles AT, Ruddy JA, et al
. Safety and reactogenicity of 2 doses of SARS-CoV-2 vaccination in solid organ transplant recipients. Transplantation 2021 Apr 9. doi: 10.1097/TP.0000000000003780. Online ahead of print.
Meshram HS, Kute VB, Shah N, Chauhan S, Navadiya VV, Patel AH, et al
. Letter to editor: COVID-19 in kidney transplant recipients vaccinated with Oxford-AstraZeneca COVID-19 vaccine (Covishield): A single center experience from India. Transplantation 2021 May 26. doi: 10.1097/TP.0000000000003835. Epub ahead of print. PMID: 34049359.
Kute V, Agarwal SK, Prakash J, Guleria S, Shroff S, Sharma A, et al
. NOTTO COVID-19 vaccine guidelines for transplant recipients. Indian J Transplant 2021;15:1. [Full text]
Billany RE, Selvaskandan H, Adenwalla SF, Hull KL, March DS, Burton JO, et al
. Seroprevalence of antibody to S1 spike protein following vaccination against COVID-19 in patients on haemodialysis. A call to arms. Kidney Int 2021;99:1492-4.
Labriola L, Scohy A, Seghers F, Perlot Q, De Greef J, Desmet C. A longitudinal, 3-month serologic assessment of SARS-CoV-2 infections in a Belgian hemodialysis facility. Clin J Am Soc Nephrol 2020;16:613-4. DOI: https://doi.org/10.2215/CJN.12490720
Ikizler TA, Coates PT, Rovin B, Ronco P. Immune response to SARS-CoV2 infection and vaccination in patients receiving kidney replacement therapy. Kidney Int 2021;99:1275-9.
Baker D, Roberts CA, Pryce G, Kang AS, Marta M, Reyes S, et al
. COVID-19 vaccine-readiness for anti-CD20-depleting therapy in autoimmune diseases. Clin Exp Immunol 2020;202:149-61.
Jeyanathan M, Afkhami S, Smaill F, Miller MS, Lichty BD, Xing Z. Immunological considerations for COVID-19 vaccine strategies. Nat Rev Immunol 2020;20:615-32.
Danziger-Isakov L, Kumar D; AST ID Community of Practice. Vaccination of solid organ transplant candidates and recipients: Guidelines from the American society of transplantation infectious diseases community of practice. Clin Transplant 2019;33:e13563. doi: 10.1111/ctr.13563. Epub 2019.
Greinacher A, Thiele T, Warkentin TE, Weisser K, Kyrle PA, Eichinger S. Thrombotic thrombocytopenia after ChAdOx1 nCov-19 vaccination. N Engl J Med 2021;384:2092-101.
Bhaskar S, Bradley S, Chattu VK, Adisesh A, Nurtazina A, Kyrykbayeva S, et al
. Telemedicine across the globe-position paper from the COVID-19 pandemic health system resilience PROGRAM (REPROGRAM) international consortium (Part 1). Front Public Health 2020;8:556720.
Elias M, Pievani D, Randoux C, Louis K, Denis B, Delion A, et al
. COVID-19 Infection in kidney transplant recipients: Disease incidence and clinical outcomes. J Am Soc Nephrol 2020;31:2413-23.
Voysey M, Costa Clemens SA, Madhi SA, Weckx LY, Folegatti PM, Aley PK, et al
. Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: A pooled analysis of four randomised trials. Lancet 2021;397:881-91.
Olliaro P. What does 95% COVID-19 vaccine efficacy really mean? Lancet Infect Dis 2021;21:769.
Islam MR, Hoque MN, Rahman MS, Alam AS, Akther M, Puspo JA, et al
. Genome-wide analysis of SARS-CoV-2 virus strains circulating worldwide implicates heterogeneity. Sci Rep 2020;10:14004.