Reinfection: Are recovered COVID patients immune to COVID reinfections?
For all intents and purposes, patients who recover from viral infections such as COVID-19 are able to develop adequate serum titers of antibodies to ward off future infections from the same virus. This process is similar to the one that follows a vaccination. Reinfection, however, might take place even among recovered patients under certain circumstances:
Reinfection post a subclinical infection:
Reinfection is always a possibility with a viral infection such as COVID-19. This is especially true if one has a subclinical infection (i.e., an asymptomatic infection). The human body does not mount much of an immune response against subclinical infections. Therefore, the body is unlikely to be able to ward off a second re-infection. According to Dr. Gangakhedkar, senior ICMR scientist, over 80% of all COVID cases in India are asymptomatic, making them more susceptible to a re-infection.
80% of all COVID cases in India are asymptomatic, making them more susceptible to a re-infection.
Reinfection within a window after the first infection:
Reinfection is also possible within the window after the first infection and before one develops antibodies. That window can vary from a couple of weeks to a few months, depending on how much the immune system was triggered. A strong immune response is likely to shorten this window. The problem, however, is that the strength of the immune response is highly variable depending on such factors as viral load and antigenicity of the virus (the ability of the virus to induce an immune response in the body).
Doctors and researchers might however be able to estimate the likelyhood of re-infection in both scenarios soon. A large population of people have recovered from the virus since it first broke out in December of 2019. Serum samples from these patients can allow them to time exactly when they begin to develop antibodies and when they develop sufficient titers and neutralizing antibodies. This study will enable experts to estimate what the window is for protection.
While discussing re-infection it is important to recognize that the COVID outbreak has taken place amidst a host of other infections. Therefore, one must realize that before a person's immune system returns to normal, the person can be infected by not just the virus, but by regular colds and flu. A couple of months may be a reasonable window of recovery, based on the available data.