MEDPAGE TODAY 2021.01.03
Right now, the U.S. is entering the next important phase of eradicating COVID-19 — administering vaccines. There are, of course, critical issues to address, such as how the vaccines will be distributed, which segments of our population should receive vaccination priority, and whether we need to continue wearing masks until herd immunity is achieved.
In addition, another important question must be answered. Should a person who has recovered from COVID receive a vaccine?
This question is relevant to all current vaccines being developed. A brief review of vaccine history reveals that new vaccine development has a success rate of about 7%. Given the fact that there are over 200 vaccines in or ready for clinical trials, at least 14 vaccines should be clinically successful. To date, Pfizer, Moderna, AstraZeneca, Novavax, Johnson & Johnson, GlaxoSmithKline, and CNBG in China have reported that 80%-95% of people taking their vaccines are protected from COVID. While one company may not be capable of producing enough vaccines for all of its customers, the fact that so many companies are reporting successful vaccine development is a tremendous outcome.
From an immunological and bioethical perspective, the are several reasons why a person who has recovered from COVID should be vaccinated. First, providing a vaccine to that person would be no different from a person who has recovered then been re-exposed or re-infected. In both cases, that individual will mount a rapid immune response and either will be asymptomatic or present with mild, manageable symptoms. In fact, re-exposure to the SARS-CoV-2 virus or receiving a vaccine might even enhance that person’s immunity to future COVID infections.
Our immune system is brilliantly designed to protect us from new and future viral infections after we have recovered from one. It contains an immunological library in our lymphatic system that stores memory lymphocytes that have been programmed to respond to almost any past infection that a person has encountered. If we are exposed a second or third time to one pathogen, these memory lymphocytes move out of retirement and rapidly prevent re-infection. Since a vaccine is designed to mimic a viral exposure without eliciting a dangerous viral infection, these resident memory cells only re-ignite the immune system and mitigate the infection — they don’t cause illness.
Equally important, upon re-exposure to a virus or receiving a vaccine, our immune system could generate even better memory lymphocytes to fight future infections. For example, it is known that the HPV vaccine Gardasil triggers a stronger immune response than exposure to the natural virus. Similarly, the tetanus vaccine triggers a more robust immune response than exposure to tetanus bacteria.
Finally, vaccines can elicit protection against several other viruses. There are a lot of data showing that people who were vaccinated against measles, influenza, or TB generate lymphocytes that even help protect them against COVID. In fact, one theory why young children do not present with severe COVID is because their normal childhood vaccinations strengthen their overall immunity.
We have no clinical evidence from other viruses to show that people who have recovered from one infection and are vaccinated will develop any harmful side effects. From an ethical perspective, there are so many complex issues regarding who should get vaccinated and in what order. Why should we add another complication of vaccine delivery?
Thus, all medically competent individuals should get vaccinated as soon as possible. In non-pandemic times, each individual should have his or her autonomous right to choose which vaccine to receive and whether to be vaccinated, even if they have been exposed to a pathogen. In this pandemic, we must let our healthcare providers stop the infections by vaccinating as many medically competent people as possible. This will accelerate the time it takes to achieve herd immunity and will return our lives to a point where we won’t need to wear masks, social distance, or quarantine.