The first corona viruses known to infect humans were discovered more than half a century ago – Why are there no vaccines against these viruses? Should we be optimistic that an effective vaccine is now being developed?
SARS-CoV-2, the recently discovered coronavirus that causes COVID-19, is similar enough to other coronaviruses that scientists make predictions about how our immune system could deal with it. But its novelty requires careful study. Similar to Sars and Mers, which cause the severe acute respiratory syndrome, the novel coronavirus originated from animals and can harm the animal lung and sometimes other organs.
In contrast, COVID-19 has caused major disruptions worldwide. As a result, at least 90 Vaccines are under development, with some already in human experiments.
How a vaccine works
A vaccine gives our body a harmless taste of the virus and alarms the immune response to produce antibodies and / or cellular immunity (T cells) that are ready to fight the infection. The idea is that the next time the virus appears, we can use a pre-built defense system that protects us from serious symptoms. We know that most people have recovered from COVID-19 have detectable antibodies in their blood.
We don’t know if these antibodies are fully protective, but a vaccine can still produce strong neutralizing antibodies, and scientists will evaluate them after vaccination. The researchers will also look for strong T cell responses in the blood of vaccinated people. These measurements will help scientists predict the effectiveness of the vaccine and will be available before a vaccine is approved.
Of course, the best way to evaluate a vaccine is to assess how well it protects people from infection. However, exposure of vulnerable groups to the virus is far too risky, so most vaccines are tested in younger people with no underlying health problems. There is ethical considerations for deliberately infecting a healthy person with a potentially dangerous virus for a vaccination attempt and these must be carefully considered.
In the course of a pandemic, a vaccinated volunteer can become infected with the novel corona virus, especially if he works in the healthcare sector. It will take time to collect post-infection protection data and compare it to people who have received a placebo vaccine.
The ideal vaccine should protect everyone and create lifelong defenses with a single dose. It would be quick to manufacture, affordable, easy to administer (nasal or oral), and would not require cooling so that non-professionals can distribute it to hard-to-reach parts of the world. In reality, we don’t quite understand how to make a vaccine that induces long-lasting protective immunity for various viruses. For some infections, we need to have a booster shot.
Aging is associated with a tired immune system that has difficulty responding to vaccinations. This also applies to people with weakened immune systems. It is therefore difficult to protect the most vulnerable. Therefore, vaccination programs that protect over 80% of the population can reduce the frequency of virus spread and protect those at risk by proxy through herd immunity. For now, The percentage of people who may have had COVID-19 in different parts of the world variesHowever, this is difficult to estimate due to the test availability.
Scientists test and confirm the safety of a vaccine before it is approved. We appreciate this for some virus infectionsexisting antibodies from a previous infection with the same virus type can cause more serious illnesses. However, there is no clear evidence of adverse effects of antibodies to SARS-CoV-2 infection.
Here are some reasons to be optimistic. First, this virus can be cured. Unlike some viruses like HIV, which embed their genome in our own and make new copies of themselves after immune elimination, we know that SARS-CoV-2 is this unable to exist in this way.
Two of the most infected patients Develop antibodies and there is evidence of virus-specific T cell responses. While we don’t yet know if these reactions are protective, these are the very reactions that can lead to immunological memory, the cornerstone of vaccination. Vaccine products are refined and enriched to trigger stronger immune responses than natural infections.
Three, mutating corona viruses Slower than viruses like influenza, and we know from Sars and Mers that antibodies can persist for at least one to two years after recovery. This is good news for an effective vaccine that may not need to be updated for some time.
There are other reasons to be optimistic. Are scientists Testing multiple approaches Therefore, there is a higher likelihood of success, and pharmaceutical companies were hired early on to increase production and develop logistics for sales before there was any evidence that the vaccine would work. This is well worth the investment as the resources for the most promising vaccines can be quickly reused after the initial clinical studies.
A coronavirus vaccine is within our reach and it is our best hope to curb transmission and create herd immunity to protect the most vulnerable. By removing its hosts for replication, we can eradicate this virus from the human population, just as vaccination previously eradicated smallpox.
Zania Stamataki, Lecturer in Viral Immunology at the University of Birmingham
This article is republished by The conversation under a Creative Commons license. read this original article.
Updated on: May 15th, 2020 14:11:50 IST
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