The presence of antibodies to the SARS-CoV-2 virus could provide some protection, but scientists need more data
Unlike diagnostic tests, which are used to confirm the presence and sometimes load, or amount, of the virus, antibody tests help determine whether or not someone was previously infected—even if that person never showed symptoms. Widespread use of such assays could give scientists greater insight into how deadly the virus is and how widely it has spread throughout the population.
It is less clear what those antibody tests mean for real life, however, because immunity functions on a continuum. With some pathogens, such as the varicella-zoster virus (which causes chicken pox), infection confers near-universal, long-lasting resistance. Natural infection with Clostridium tetani, the bacterium that causes tetanus, on the other hand, offers no protection—and even people getting vaccinated for it require regular booster shots. On the extreme end of this spectrum, individuals infected with HIV often have large amounts of antibodies that do nothing to prevent or clear the disease.
At this early stage of understanding the new coronavirus, it is unclear where COVID-19 falls on the immunity spectrum. Although most people with SARS-CoV-2 seem to produce antibodies, “we simply don’t know yet what it takes to be effectively protected from this infection,” says Dawn Bowdish, a professor of pathology and molecular medicine and Canada Research Chair in Aging and Immunity at McMaster University in Ontario. Researchers are scrambling to answer two questions: How long do SARS-CoV-2 antibodies stick around? And do they protect against reinfection?
Early on, some people—most notably U.K. Prime Minister Boris Johnson (who has the virus and is currently in intensive care) and his government’s scientific adviser Patrick Vallance—touted hopes that herd immunity could be an eventual means for ending the pandemic. And although it appears that recovered COVID-19 patients have antibodies for at least two weeks, long-term data are still lacking. So many scientists are looking to other coronaviruses for answers.
So, the bottom line is ... that there really isn't a bottom line right now. All that shouting about 'herd' immunity? Perhaps this article helps explain why so many public health people were warning against that as a 'policy.' With a 'novel' virus it's more of a crap shoot. There's a reason why there's no vaccine for the common cold.