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COVID-19 Vaccine Updates
With input from Dr Monica Vasudev
1279: Delaying Second COVID-19 Vaccine Dose
- There is a proposal to delay the administration of the second dose of COVID-19 vaccines. This has been proposed as a strategy to increase the number of people who get some degree of protection from a single inoculation with the Pfizer/BioNTech or Moderna vaccines
- Advocates of the proposal argue that getting some degree of protection to a greater number of individuals is valuable, especially when cases and hospitalizations continue to surge and a more contagious variant has emerged.
- Opponents, on the other hand, raise concerns about diverting from the two-dose schedule that has been investigated in clinical trials, including a lack of data on long-term protection from a single dose. Additionally, a longer interval between the two doses could increase resistance of SARS-CoV-2.
- The experts stated that limited supply, distribution bottlenecks, and thousands of new infections daily urged them to change their stand on administering COVID-19 vaccines as per the two-dose clinical trial regimen. They also cited a study in the New England Journal of Medicine which suggests 80% to 90% efficacy for preventing SARS-CoV-2 infection after one dose of the Moderna vaccine.
- However, others say that after one dose, the immune system is learning, but its not ideal. Thats why the second dose is needed.
- Another strategy that has been proposed to extend the current supply of COVID-19 vaccines to more Americans involves splitting the current dosage of the Moderna vaccine in half.
- Mike Tyson famously said: “Everybody has a plan until they’ve been punched in the mouth.” One of the expert says that in terms ofCOVID-19, we’re being punched in the mouth again and again. It’s time to change the plan. A single vaccination should be given now and the second shot should be deferred until more doses of the vaccine become available.
- The clinical trial results for the Pfizer and Moderna vaccines are reassuring. While the trials intended to test the effectiveness of two shots given about a month apart, both showed that the first shot had a considerable benefit beginning around 10 days afterward. By the time of the second shot, the first was already 80% to 90% effectivein preventing COVID-19.
[Excerpts from Medscape; The Washington Post]
1280: Should a person who has recovered from COVID-19 receive a vaccine?
- A brief review of vaccine history shows that new vaccine development has a success rate of nearly 7%.
- There are more than 200 vaccines in or ready for clinical trials, and at least 14 vaccines should be clinically successful.
- Till today, Pfizer, Moderna, AstraZeneca, Novavax, Johnson & Johnson, GlaxoSmithKline, and CNBG in China have reported that 80%-95% of individuals taking their vaccines are protected against COVID-19.
- While one company may not be able to produce enough vaccines for all of its customers. Therefore, several companies reporting successful vaccine development is a tremendous outcome.
- From an immunological and bioethical perspective, providing a vaccine to a post-COVID person would be no different from a person who has recovered then been re-exposed or re-infected. In both cases, the individual will mount a rapid immune response and either will be asymptomatic or develop mild, manageable symptoms. Re-exposure to the SARS-CoV-2 virus or receiving a vaccine might even boost the persons immunity to future COVID infections.
- The immune system contains an immunological library in our lymphatic system that stores memory lymphocytes which respond to almost any past infection that a person has encountered. If one is exposed for the second or third time to a pathogen, the memory lymphocytes prevent re-infection.
- A vaccine is designed to mimic a viral exposure without eliciting a dangerous viral infection. Hence, the resident memory cells only re-ignite the immune system and mitigate the infection and don’t cause illness.
- When there is re-exposure to a virus or a vaccine is administered, the immune system could generate even better memory lymphocytes to fight future infections. For example, it is known that the HPV vaccine induces a stronger immune response than exposure to the natural virus. The tetanus vaccine triggers a stronger immune response than exposure to tetanus bacteria.
- Vaccines can elicit protection against several viruses. Data suggest that people who were vaccinated against measles, influenza, or TB generate lymphocytes that even help protect them against COVID-19.
- There is no clinical evidence from other viruses to show that individuals who have recovered from one infection and are vaccinated will develop any harmful side effects.
- All medically competent individuals should receive vaccination as soon as possible. In non-pandemic times, every individual should have his or her autonomous right to choose which vaccine to receive and whether to be vaccinated or not, even if they have been exposed to a pathogen. In this pandemic, we must enable our healthcare providers curb the infections by inoculating as many medically competent people as possible. This will speed up the attainment of herd immunity.
[Excerpts from Medpage Today]
Dr KK Aggarwal
President CMAAO, HCFI and Past National President IMA