Everything You Want to Know About COVID-19 and Immunity
Immunity from COVID-19 – we all want it, not only for ourselves, but for our community. But how do we reach this utopia of normalcy? We talked with Alex Benjamin, MD, with LVPG Infectious Diseases and Chief Infection Control and Prevention Officer at Lehigh Valley Health Network (LVHN), to get the details on what is known and what is yet to be discovered about COVID-19 and immunity.
What is herd immunity?
Herd immunity is when a large enough portion of a population develops immunity to an infectious disease. This provides protection to people who are not immune by reducing the chance that they will be exposed to the virus. Immunity may come as a result of prior illness or a vaccination. Some members of the population may not be able to get vaccinated due to underlying medical conditions and therefore rely on herd immunity to be protected.
How many people need to be exposed to COVID-19 to reach herd immunity?
It is hard to estimate how many people have been exposed to COVID-19. The number of positive COVID-19 tests that we’ve seen at LVHN is 0.7%–0.9% of the total population of our region. It is unclear what percentage of the population needs to be immune or exposed to COVID-19 to guarantee herd immunity. For other diseases, including polio, smallpox, measles and rubella, herd immunity requires 80%-94% of the population be exposed.
Which is likely to come first – herd immunity through exposure or a vaccination?
It is difficult to say. If there are more surges of COVID-19 in our region, herd immunity may come from disease exposure. It’s estimated that the earliest we could have a COVID-19 vaccine is in early 2021. Once that happens, there may be a long delay (months) between an available vaccine and being able to distribute it to the entire population. During the wait, more and more people will become exposed to the disease. Depending on how severe the disease is in the population, it may lead to increased hospitalizations and closing of businesses and schools.
Should I expose myself to COVID-19 to build immunity?
We cannot predict how severe the disease will be in any age group, race or gender. Furthermore, we have not been able to determine how long immunity will last after disease exposure. Usually after having an infection, you develop antibodies that protect you from future infections/exposures. However, we now know that some people who are exposed to the virus will not have detectable antibodies in their blood after some time has passed. We don’t know if these people who lose their antibodies are truly susceptible to becoming reinfected.
What are the long-term effects of COVID-19?
Reports of chronic symptoms after COVID-19 infection are becoming more common. These include persistent fatigue, low-grade temperatures, myalgias (muscle aches and pains), “brain fog” and cough. Our current understanding is that this could be due to an intense immune response to COVID-19 that persists beyond any evidence of active viral infection. It is too early to determine how long these symptoms may last.