Q:

If Covid antibodies disappear after 2-3 months, will a vaccine still be effective?

It looks like there have been studies in China and also in Spain that suggest antibodies don't last very long or could disappear after some time. What does this mean for the effectiveness of a potential vaccine? Could the effects wear off after a few months? Is this different from other diseases we get vaccinated for? I know we need to update the flu vaccine every year, but I thought that was due to mutations in the virus, not from antibodies breaking down. I am not a scientist, can anyone ELI5?

A:

Humans don't constantly produce antibodies for a pathogen when the pathogen has been gone for a while. They just store the 'recipe' for making the particular antibody in memory T cells.
If the antigens that the virus contains mutate enough to not work for the antibodies an immune person has developed. Then the process starts over and the immune system will have to 'create a new recipe'.
Each new host creates a possible scenario for a coronavirus such as the current SARS-CoV-2 to mutate and develop different antigens that may cause a second wave requiring humans to develop new antibodies in our immune system and new vaccines to be distributed.
Though coronaviruses do not mutate as quickly as other viruses such as the influenza virus. It is still possible that SARS-CoV-2 having caused such a large pandemic, may develop a new strain.

