Dozens of companies and countries around the world are developing a coronavirus vaccine. And some of them have already begun clinical studies, bypassing the stage of animal testing.
For example, according to Olga KARPOVA, head of the Department of Virology, Moscow State University. Lomonosov, the Russian vaccine will appear in a couple of months and will be effective against the three most dangerous coronaviruses at once: SARS, MERS and COVID-19. According to the virologist, it will be a recombinant vaccine. Do it like this. The plant virus of tobacco mosaic acts as a platform. This, by the way, is the very first virus discovered by humans. In nature, it resembles a stick, but virologists make it spherical by a special heating technology. The result is a round nanoparticle with a size of 500-600 nanometers, which adsorbs proteins of any coronavirus on itself.
On this basis, proteins made by genetic engineering methods are planted, which have a sequence that is part of a number of coronaviruses - SARS, MERS, and COVID-19, and even those that have not yet manifested themselves, but we know that they live in the organisms of bats and may someday burst into our lives.
And all this sounds, of course, very promising, but in the scientific community there is one very seditious question:
Could it be that the vaccine worsens the course of the disease for which it was created? To answer this question, we need to become familiar with the phenomenon of "antibody-dependent intensification of infection". The phenomenon of antibody-dependent intensification of infection, (abbreviated as ADE) was described by scientists back in 1964. The bottom line is simple - in the presence of specific antibodies, some viruses multiply faster.
Subsequently, it has been shown that when antibodies that do not neutralize the virus sufficiently bind to the viral particles, it leads to more efficient cell infection, and as a result, to increased viral replication and pathogenicity. Subsequently, this phenomenon was observed for many other viruses. To simplify even further, the essence is this - after vaccination, the disease progresses worse than if there was no vaccination. Now let's look at specific examples with specific links to scientific articles.
The coronavirus family includes 40 viruses, of which 7 viruses are capable of infecting humans. Of these seven, four viruses (229E, NL63, OC43, HKU1) cause the common cold, and are responsible for 10-15% of colds. 229E and OC43 were discovered in the 60s, another (NL63) was first discovered in 2004 in the Netherlands, and the last (HKU1) in 2005 in Hong Kong. The fifth SARS coronavirus was responsible for the 2002 SARS epidemic that began in China, and the sixth MERS was responsible for the Middle East respiratory syndrome epidemic that began in 2012 in Saudi Arabia. The seventh SARS-CoV-2 virus is responsible for the current 2020 pandemic.
And this is what virologists describe in scientific articles on this topic. At the initial stage of infection, the SARS coronavirus does not infect macrophages, those very immune cells. But when the immune system starts making antibodies against the virus, they help the virus enter macrophages, leading to more severe infections. Work on a coronavirus vaccine has been underway since the beginning of the SARS epidemic.
In a 2006 study, the SARS coronavirus vaccine was effective in young mice. But in old mice that were vaccinated against SARS and then infected, the vaccination led to an immune pathology of the lungs. The same results were obtained in the 2011 and 2012 studies with several types of vaccines. Immune pathology of the lungs has also been observed in preclinical trials of the vaccine in ferrets and monkeys.In a 2008 study, the SARS coronavirus vaccine resulted in severe pneumonia after infection. In a 2004 Canadian study, ferrets vaccinated against the SARS coronavirus and subsequently infected with the coronavirus experienced significantly more severe liver inflammation (hepatitis) compared to unvaccinated ferrets.
All of these test failures are attributed to the phenomenon of antibody-dependent exacerbation of infection. For example, in a 2007 Chinese study, the SARS coronavirus vaccine performed well in animals, but in a human cell line, the vaccine resulted in increased cell infection. These results have been confirmed in other studies as well.
A similar picture was observed with the MERS coronavirus in a 2016 study. The vaccine resulted in lung immune pathology in mice when infected with the coronavirus. In a 2017 study, rabbits vaccinated against the MERS coronavirus experienced increased pneumonia. And when uninfected and previously unvaccinated rabbits were transfused with the blood of vaccinated rabbits, they also experienced the same increased pneumonia when they encountered infection.