Will a coronavirus vaccine be a ‘cure’ for the pandemic?
The answer to this is more complicated than one might think and centers around the question of the strength and longevity of the immune response.
By MAAYAN JAFFE-HOFFMANScientists develop a vaccine against the coronavirus disease in Saint Petersburg(photo credit: REUTERS) In recent weeks, Israel has signed two agreements to be among the first to receive COVID-19 vaccines when they become available, first with Moderna and then with Arcturus.But will a vaccine for the novel coronavirus be a “cure-all” solution to the pandemic?The answer to this is more complicated than one might think and centers on the strength and longevity of the immune response.Earlier this month, a Tel Aviv University team of researchers examined the development of antibodies binding to two different targets on the coronavirus in patients. They found that over the long term, patients developed antibodies at the same level regardless of whether they had a severe or mild case of COVID-19.“Patients with mild, moderate and severe COVID-19 all developed the same level of antibodies,” Prof. Ariel Munitz of the Department of Microbiology and Clinical Immunology at TAU’s Sackler School of Medicine said in a press release. “This is important, because one might have thought that the severely ill became so sick because they did not develop a sufficient amount of antibodies, and were thus unable to combat the virus effectively.”Moreover, the research showed that levels of the antibody targeting the viral spike protein that binds the virus to human cells remained high in the patients’ blood for two months following contagion – possibly indicating the formation of immunological memory.These “IgG-type antibodies play an extremely important role in the immune response because they can neutralize the protein that binds the virus to human cells to enable contagion, thereby preventing the virus from penetrating the cells,” explained Prof. Motti Gerlic, who worked with Munitz on the study. His team has not yet examined how these antibodies actually work, he said, and they still do not know whether or not they neutralize the virus, “but the facts that these antibodies are quickly produced in all patients, and stay in the blood for a long time, suggest that they provide some level of immunity.”But not all scientific research has yielded the same results – and here, too, there are still many questions.ACCORDING TO Prof. Cyrille Cohen, vice dean of the Mina and Everard Goodman Faculty of Life Sciences at Bar-Ilan University, multiple studies, including a recent one published by King’s College London, found that neutralizing antibodies declined significantly after a few months, which calls into question the extent to which immunity to the virus is long-lasting.“People all over the world... already found out that a large fraction of patients who were ill recovered and had a detectable antibody response,” but that “in matter of three months or so the antibody levels were reduced, sometimes to undetectable levels,” Prof. Itay Ben Har, acting director of TAU’s new Center for Combating Pandemics, told The Jerusalem Post.
“This would not be surprising,” Cohen said, adding that among the seven known members of the coronavirus family, there are four that cause common colds to which our bodies do not necessarily mount long-lasting immunity.“This explains why sometimes we may be sick with the same disease – the same cold – several times during our lives,” he said.On the other hand, the scientific community has not yet explained why some people seem to be already “immune” to COVID-19, meaning they become infected but develop few or no symptoms, he added.This could be a result of some kind of cross reaction, meaning that “because you mounted a good response to a common cold caused by another member of the coronavirus family, you now have some immunity to COVID-19,” Cohen said.It could also be that these people “have a good T-cell response,” he said.Indeed, growing evidence suggests that T cells provide the strongest and longest-lasting immunity to the novel coronavirus and that people who recover from it could show strong T-cell responses but with no detectable antibodies – something that is still being researched.Most of the major vaccine makers are saying that for now, their vaccines have elicited some kind of immune response, similar to the responses seen in people who have recovered from the virus.So, then the question becomes for how long will the vaccine be effective?“WE HAVE vaccines that require boosting, like the tetanus vaccine,” Ben Har said. “There are also vaccines that are short-lived and need to be readministered every year. The best known is the flu vaccine. But this is not because of failure of our immune system to make an immune memory, but because every year the virus changes.”He does not believe the coronavirus mutates so rapidly, but some of his colleagues disagree, and “at this point, we cannot really say which people are right,” he said.“I think it will be like the flu, and we will have to live with it forever,” Dr. Rivka Abulafia-Lapid, a senior virology lecturer at the Hebrew University of Jerusalem, told the Post. She described a future where a committee meets each year to decide on what strains of coronavirus are likely to attack. It could be that different strains would appear in different parts of the world, she said.“The people most likely to develop severe cases will surely need to get vaccinated,” she said.Therefore, the vaccine would not be a cure, just a preventative measure for that year, Abulafia-Lapid speculated.But an insider with ties to the US National Institutes of Health said he is confident the vaccines will work at least in some capacity. Sometimes vaccines do not prevent diseases but reduce their severity and the likelihood of dying from them, which would be a good start for any coronavirus vaccine, he said.He described the vaccine candidates currently in development as “vaccines 1.0” and said any vaccine that is revealed in the next year will not be perfect and will need further development going forward.
