“Science appears calm and triumphant when it is completed; but science in the process of being done is only contradiction and torment, hope and disappointment.” － Pierre Paul Émile Roux, French bacteriologist and developer of the first effective treatment for diphtheria”
I wish we knew the antibody level that gives us immunity against COVID-19. It would make life a lot simpler. Our other vaccine-induced immunities, like measles, mumps, chicken pox, and even tetanus, can be measured by the amount of antibodies circulating in our blood. But as as is often the case with this “novel” SAR-CoV-2 virus, the virus cause of COVID-19, the story is much more complicated. Why can’t we test for SARS-CoV-2 antibody levels? (1)
The answers are that 1) a reliable measure of SARS-CoV-2 antibodies has not yet been standardized, and 2) we don’t know what level of COVID antibodies actually gives us immunity; protection from infection and illness. The FDA has not yet “authorized” a standard test to be used as a diagnostic test for the general public.
Measles vaccine and other virus vaccines are made of killed, inactivated, or attenuated (weakened) whole viruses. The killed virus vaccine tricks our immune system into thinking that we are infected by alien antigens, and we produce antibodies to bind up or kill the whole virus if it infects us in the future. The level of antibodies which protects us from disease after a measles vaccine is known, the blood test to measure the level is standardized, and the test is easily done by all labs.
The vaccines against COVID are NOT whole viruses. They are mRNA vaccines directed NOT at the whole virus, but at just the spike proteins which the virus uses to attach to, infect our cells and cause illness. Developing a reliable test of antibody to just a specific portion of the COVID virus, the spike proteins, is more difficult, requires a more complex laboratory procedure, and is not yet ready for prime time. One hurdle is that the spike proteins of the COVID variants, . . . well, . . . actually vary from one another, hence the name “Delta variant”. So, the antibodies we produce to each variant may be different and may be only measurable by different tweaks in the lab. The good news is that there are enough similarities between the variant spike proteins that all the current vaccines are protecting us from all of the variants (“so far”).
Another complication to the antibody story is that there are different kinds of antibodies produced by our immune system. We know from other infections that some antibodies kill the alien cells (“neutralizing antibodies”) while other antibodies just bind or “wrap up” the virus antigens and that blunts their ability to cause symptoms.. This difference of antibody effectiveness may be the explanation of why some COVID-vaccinated people get a second infection, but don’t develop a serious, even lethal illness. How does that happen?
Welcome to a brief introduction to a critical part our immune system, the B cells. B cells are our immunity “memory cells”. They remember which alien antigens (from vaccines or natural infection) have invaded us before, recognize them as unwanted, and the B cells transform themselves into antibody producing cells. This process takes about 3-5 days after infection. These new antibodies from the transformed B cell can blunt the symptoms of serious illness. Since the transformation of B cells into antibody producing cells can take 3-5 days, a vaccinated person may get infected a second time (“waning neutralizing antibodies”) and show only mild symptoms or a positive nasal swab test, but the antibodies produced 3-5 days later by the B cells bind enough of the virus to prevent serious symptoms, hospitalization, and death. “How much antibody is enough” to accomplish this is not currently known.
It is intriguing to remember why the SAR-CoV-2 virus is labeled a “novel” virus. It is only just the second known coronavirus that causes serious illness, hence the number 2 in its name. Most corona viruses, of which there are very many, simply cause common cold symptoms. Our current research into developing COVID-19 vaccines may someday lead to a vaccine for the common cold; not a lethal disease certainly, but one of staggering economic effect throughout the world (2) .
Perhaps in the future one of our children, or more likely one of our grandchildren, will correctly pick the stock of the pharmaceutical company that develops a vaccine for the common cold. Having missed the Moderna stock price surge myself, I can only wish them better luck in the “cold vaccine sweepstakes”.
“Hope springs eternal”, I guess.
(1) jamanetwork.com; Oct. 21, 2021
Medical News and Perspective, Jennifer Abbasi
(2) “We conclude that the economic cost of lost productivity due to the common cold approaches $25 billion, of which $16.6 billion is attributed to on-the-job productivity loss, $8 billion is attributed to absenteeism, and $230 million is attributed to caregiver absenteeism.” T.Bramley, J Occup Environ Med 2002 Sept; 44(9):822-829