John Whyte, MD, MPH; Alexander Greninger, MD, PhD
In a new study, 85% of a Seattle fishing boat crew were infected onboard with COVID-19 in May. The entire crew had tested negative for infection and had blood drawn before departure. Upon return, the three people who had neutralizing antibodies before departure were not infected on the ship.
The big question is, how long are COVID-19 antibodies protective? It depends on the titers, or the concentration of antibodies, in an individual's blood.
People with more severe COVID-19 infection probably have more antibodies, which could possibly protect them from reinfection for a year or more. Milder infections lead to fewer antibodies and could possibly provide protection for up to 6 months.
Reinfection of COVID-19 is possible. Studies indicate that about 10% of people with mild infections show little immune response, increasing their risk for reinfection.
Reinfections are often milder and may be asymptomatic.