The best news regarding COVID-19 occurred these past couple of weeks. Scientists are hesitant to be too excited. But the most recent research is promising.

Much of the immune response to COVID-19 has focused on the production of antibodies. But emerging research is revealing that T cells may be the primary drivers of our immune response. We’ve mentioned this during the past month. But continued examination of the evidence is making this fact clearer and worth understanding. There are many factors to consider.

We’ve always wondered why there was such a broad range of response to COVID-19. Some people have no symptoms. Some get mildly sick and others become deathly ill. While much of the answer lies within the fact that immunocompromised individuals are more susceptible, there seems to be more at play.

T cells have memory. When exposed to a virus, they recall the exposure for future immune response. Interestingly, there may be some cross immunity in this regard. The coronavirus family is somewhat large and exposure to one may provide some protection to another. People have a broad range of past exposures and this may partially explain the broad range of immune responses to COVID-19. Even how a person responded in the past to common cold exposure may factor into COVID-19 immune response. The pattern of a person’s past exposures could explain how their body has trained their immune systems to respond in the future. But there’s more.

While B cells produce antibodies that neutralize invading virus, T cells sort of attack infected cells and provide other coordination of helper cells that fight it off. Although there are two sides to this response, we generally test B cell response because its easier to test. Interestingly, the emerging research, published in the prestigious Cell journal, is finding robust T cell responses even in the absence of antibodies. So, someone may have a negative antibody test but still may have some immunity if there were past exposures to stimulate T cell responses.

T cell response received less attention months ago. The reason is that T cell response is less straightforward to measure than B cell antibody responses. Experts also consider it less important when studying for vaccine development.

T cell response is also generally longer lasting for the most part. While it is impossible to know how long immune responses will last with COVID-19 in particular at this point, the very fact that T cell response is a primary driver for COVID-19 response is promising.

Certainly, we are still struggling to understand the infection. But when you hear about immune responses, understand that antibodies are simply the easiest indicator to track. They are also highly variable from person to person. The latest studies regarding the role of T cells provides hope that immunity will be longer-lasting than we first anticipated. It may just vary in severity from person to person.

There is this growing body of evidence that a vaccine can be developed and that long-term immunity can be achieved. The big unknown question is how many people have developed an immune response and we don’t know it. The suspicion is that more people have been infected than we realize based on this emerging research. It is a complex task to factor in immunity by direct exposure, varying levels of immune response and cross immunity from other coronaviruses. If that ends up being the case, then the death rate is lower than we expected. But again, that is still the big unknown and we’re still not out of the woods until a satisfactorily vaccine is developed.