Like everything else in our world, antibody responses to the current coronavirus strain seems be to be getting politicized. It may turn out that there are red and blue antibodies. A good primer on antibodies is given in the Wall Street Journal by a physician and a scientist. (WSJ Article) As they point out, if there isn’t a strong antibody response, then hopes about a vaccine are likely foolish. But it certainly appears from the research that I read and report on here, that there is strong antibody development, particularly in regard to serious coronavirus illness.
The human immune system is a marvel of complexity and layered defense. Some of that defense is physical–against a respiratory pathogen it can include secretions and cell layers in the nose, mouth, and throat areas, which are part of the innate immune system. For more serious infections, the adaptive immune component develops specific cells and complex biochemicals called antibodies which are capable of fending off a specific pathogen. Once we have been infected and recovered, a few of those adaptive immune system cells remain, as sentinels if you will, to detect a return of that pathogen and marshal immune forces to again defeat it. Because many respiratory viruses have several strains and can mutate to create new strains, the immune system tends to create defenses that aren’t too specific to an exact strain, but have the capability to recognize and act against multiple strains. Immune system defenses, including antibodies, may tend to wane over time, particularly if there is no reinfection. Why should the body waste energy defending against a non-existent threat.
Humans are regularly infected by various strains of coronavirus and therefore regularly develop immune defenses against such infections. We have reported on several studies that identified antibodies and T-cells active against the common strains of coronavirus. This paper reports on a study, over a number of years, to ascertain infection by coronavirus. (JID Article) While not specifically studying immune response, it lays the groundwork for understanding the nature of infections and defenses. Human-infecting coronavirus have been identified for over 60 years but have certainly been infecting humans for many years prior to their recognition. They have been believed to cause mild illness at worst, but you have to suspect that they may have caused severe respiratory illness in some persons, but the illness was attributed to influenza or other causes.
This study was following children in the Ann Arbor Michigan area since 2010 to get a better understanding of the dynamics of coronavirus infection. Because coronavirus infection was believed to be seasonal, in the early years of the study, surveillance was conducted primarily in fall and winter months, but since 2014 has been year round. Specimens collected as part of the study were tested for four common coronaviruses and other respiratory pathogens. Coronavirus was responsible for a relatively low proportion of all acute respiratory illness, from 8.3% to 16.3% in a given year. Other pathogens may also have been present and accounting for the same illness. Only 2.5% of infections occurred from June through September, so there was a strong seasonal pattern. There was significant variation from year-to-year among the four common strains, which does suggest that in a year with high prevalence of a strain, antibodies and other defenses were likely developed which limited re-infection with that strain. Incidence was highest in children under age 5. 5% of cases in adults and 20% in children resulted in seeking medical help. Only 10% of infections resulted in what might be considered serious illness. One variant was more likely to produce serious illness. This study gives us some idea of what we could expect from this new coronavirus. But since it appears to cause less illness in children and more in infirm elderly persons, you wonder if the same seasonal pattern will appear.
There are very standard tests to detect antibodies. Like every test, they should be validated for accuracy. There are tests that are highly accurate. Studies of antibody prevalence often use multiple tests. So the reality is that we can have a good level of confidence that both at an individual level the tests are telling a person if they have been infected and have immune defenses, and at a societal level, that a certain number of people have been infected and recovered, which obviously has a bearing on policy development.
Vaccines can aid the immune system by feeding it weakened or parts of an infectious agent to safely prompt development of antibodies and other immune components against that agent. Some newer vaccines attempt to just tell the immune system to make this or that antibody. As the Wall Street Journal commentary points out, there is little reason to believe that if the body couldn’t for some reason create antibodies to COVID 19, a vaccine would make it do so.
Now back to the politicization point. Some people seem determined to keep us scared out of our wits and locked down forever. I have no idea why. So these people raise issues about the strength of antibodies, the accuracy of tests, and even whether people develop antibodies. Minnesota Department of Health officials have been guilty of this and did it again at yesterday’s briefing. It would be one thing to say there is room for further refinement of the science around coronavirus antibodies. But if you are truly “following the science”, it is clear that people do develop antibodies and that those antibodies will prevent reinfection from this strain and any mild mutations. And while it is unclear how long antibodies will last, if people are periodically challenged by the infectious agent, the immune defenses are revitalized, as studies show occurs with the common strains of coronavirus.
Policy now should be based on the presumption that people develop antibodies and that those antibodies will be adequate to deter re-infection. It should further be assumed that individuals can be accurately identified as having developed immunity, and that large scale antibody testing can reveal how widespread the infection has been in a population.