We’ve had some of these stories in the headlines recently, but I wanted to highlight two of them here. It seems that what we all expected would be the case, that is, most people who contract the virus will recover and then maintain long-term immunity against reinfection, it will not work. A Chinese study published in Nature last week suggests that antibodies to the virus may last only a few months.
Antibodies, protective proteins produced in response to an infection, can last only two to three months, especially in people who never showed symptoms while infected.
The conclusion does not necessarily mean that these people can be infected a second time, several experts warned. Even low levels of powerful neutralizing antibodies can be protective, as can T and B cells of the immune system.
But the results offer a strong note of caution against the idea of ”immunity certificates” for people who have recovered from the disease, the authors suggested …
Antibodies to other coronaviruses, including those that cause SARS and MERS, are believed to last about a year. Scientists hoped that the antibodies to the new virus could last at least as long.
Fox News today published a story in which an infectious disease specialist from Columbia University reacts to the Chinese study:
“When you get an antibody test, we really don’t know enough to make sure you’re safe. And I think the more we learn about antibodies, the more we begin to say that we are not so sure that it is safe, “Dr. Daniel Griffin, an infectious disease specialist at Columbia University Medical Center, told Fox. News…
“Many of us were quite disturbed when we saw this study outside of China, which actually showed that in a number of individuals, particularly in these individuals with milder diseases, we are concerned with silent spreaders, that these individuals were losing their antibodies they protect after just a month or two, ”Griffin said.
As the Times story suggests, even low levels of true Antibodies may be protective, but a second study published by Nature specifically stated that the plasma collected from most people recovering from the virus did not have enough of those antibodies to be strongly protected: “Most convalescent plasmas obtained from Individuals recovering from COVID-19 itself do not contain high levels of neutralizing activity. ” The abstract continued: “However, rare but recurrent RBD-specific antibodies with potent antiviral activity were found in all individuals evaluated, suggesting that a vaccine designed to elicit such antibodies could be widely effective.”
There is a good video that explains this second study here. The bottom line is that up to a third of the people who recovered from the virus did not appear to have enough antibodies to immunize them against subsequent infections. But it seems that the sicker people had, the more antibodies they had. Therefore, seriously ill patients may have much more resistance than those with minimal symptoms. Furthermore, the researchers identified some specific antibody proteins that were highly effective in blocking the virus. This suggests that it should be possible to design a vaccine that specifically generates these highly effective antibodies and therefore gives people greater immunity.
So not all is bad news, but in combination these two studies seem to suggest that people who have had mild cases of coronavirus may not have much protection or may not have it for a long time. It is further evidence to suggest that this is not really going to end anytime soon, unless we can come up with an effective vaccine.
