When the pandemic was about to last two years, people began to discuss what to do next. Opening up, booster vaccination, therapeutic drugs and antibody testing have become the focus of discussion in China recently. And It is difficult to find the answer to these questions. Recently, we had the honor to interview Dr Dorry Segev. As a senior expert in surgery and epidemiology, how will he view these questions?
Dorry Segev, MD, PhD, is the Marjory K. and Thomas Pozefsky Professor of Surgery and Epidemiology and Associate Vice Chair of Surgery at Johns Hopkins University. He is the founder and director of the Epidemiology Research Group in Organ Transplantation (ERGOT), the largest and most prolific group of its kind in the world. Dr. Segev was the first to demonstrate the survival benefit of incompatible kidney transplantation across the United States, and is responsible for the first HIV-to-HIV transplants in the United States. His NIH-funded research includes kidney exchange, desensitization, long-term donor risk, access to transplantation, expanding transplantation including HIV+ donors, geographic disparities, post-transplant outcomes, and the intersection between transplantation and gerontology. With a graduate degree in biostatistics, Dr. Segev focuses on novel statistical and mathematical methods for simulation of medical data, analysis of large healthcare datasets, and outcomes research.
Q1. When can we open the country? What should we pay attention to after opening up?
Dr Segev: The most important thing to pay attention to with the pandemic is the population prevalence. This is, how many cases do we have, and are cases going up, or are cases going down? I think when cases start to come down, once they reach a certain level, we can feel much more comfortable. One way to ensure that cases start to come down is to do lockdowns to make sure people don’t interact with other people and continue to spread the disease. However, once we get some control, if we are able to do mandated indoor mask use and vaccination, that gives us some freedom to be around other people without having to worry that we are continuing to spread the virus.
Q2. Should we take the booster dose based on the individual antibody level, or the antibody duration that come from the data ?
Dr Segev: For the general population, we can take boosters based on data that come from the general population. On average, it seems like out to about six months, our antibody levels drop to the point that we need a booster. So if you look like the general population, it is reasonable to do this at six months. However, for specific populations - for example, for people who are immunocompromised, for people who have higher risk with their work, for people who have a higher risk that their antibody levels would drop faster - for those people it is very reasonable to check their antibodies and give them a booster when the antibody level falls below a certain level.
Q3. Is it possible that the booster dose needs to be taken every year? Besides antibody level, is there anything else that can be used to evaluate individual immunity?
Dr Segev: There are a few reasons why we might need boosters. One of them is the reason we have now, which is there is a lot of virus everywhere, and since we are still in the middle of a very active pandemic, we need antibodies. That is the key component of the immune system that is helping us right now. That is the early immune response. As long as we have a lot of virus out there, we will continue to need antibodies, and we know that antibodies drop after getting a vaccine, so we will continue to need boosters to bring up our antibody levels.
Now, once the case load drops, and we are out of this pandemic and it reaches an endemic form, we may be able to rely on other components of our immune system, the later immune response from T-cells and memory B-cells. That is much more durable. That lasts much longer after vaccination. If we are not in a very active pandemic, we will not need to keep our antibody levels up and to have such frequent boosters.
The other reason we might need a booster is if there are new variants that don’t respond to the current vaccines that we have, just like we always need a flu shot because there are new variants of flu that we need to be protected from. If that happens, then we will need a new booster for those variants.
Q4. CDC recommends the immunocompromised people to receive additional dose. How should we protect the immunocompromised people?
Dr Segev: For people with a compromised immune system, there are two goals. One is to help them reach the level of immunity with initial vaccination that everybody in the general population reaches with, for example, two doses of the mRNA vaccine. Immunocompromised people may need three doses, or they may even need to change their medication to help them respond to the doses of the vaccine. We are currently doing some NIH funded trials to better understand how to reach initial immune levels in immunocompromised patients. For example, we study patients who have had organ transplants.
The other option for immunocompromised people who cannot respond to the vaccine (and there will be millions of them), is that they need to seek other levels of protection. One way to do this is through monoclonal antibodies, and there are emerging strong data that getting monoclonal antibodies pre-exposure can protect people who cannot mount a vaccine response.
The other way to do it is to reduce the virus prevalence in the entire community, which means all of us with competent immune systems have to get vaccinated, boostered, use masks when masks are appropriate, etc.
Q5. Do you think the listing of molnupiravir, a new oral drug, will accelerate the end of this pandemic?
Dr Segev: Obviously, having a new oral drug as treatment is very encouraging, because it means that people who get COVID-19 are likely to have a less severe infection. However, this is only treatment. Remember that if somebody gets COVID, by the time they get symptoms, they have already spread the disease to many people for days, if not maybe even one full week. So I think that new treatments are exciting because they will reduce the morbidity and mortality associated with the pandemic, but they don’t reduce the spread, and we still need to focus on vaccines to reduce the spread.
Q6. Some people try to take medicine as post exposure prevention in stead of vaccination. Do you think that's right?How should we use vaccines and medicine correctly?
Dr Segev: One mistake people are making is to think that I don’t need the vaccine because if I get exposed then I can just take post-exposure prophylaxis. The problem is, Firstly, you don’t know when you got exposed. Of course, there are some instances where you do know you got exposed, but there are many instances where you could be getting exposed and you don’t know you have been exposed. So that is problematic. And Secondly, if you are not protected when you are exposed, you are shedding virus and potentially spreading that virus to other people.
It is still absolutely the most important thing to have everyone get vaccinated, and until everyone is vaccinated and until the numbers drop substantially, to make sure people when they are indoors around strangers, that they are wearing masks and practicing the behaviors that we know reduce the spread of this virus.
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