Friday, 22 May 2020

Is a Vaccine for Sars-Cov-2 Going to be a 'Magic Bullet'?

I do feel that I have been urging caution about whether developing a vaccine (or several vaccines) will be the 'magic bullet' to eradicate the Covid-19 pandemic. There is an interesting article, bringing together many of the identified problems (https://www.theguardian.com/world/2020/may/22/why-we-might-not-get-a-coronavirus-vaccine). It is pointed out that we don't always get timely production of a vaccine for a viral infection, even when the disease is one that attracts considerable attention. For example, HIV has been known about for 30 years but we have no vaccine for AIDS. It has also taken 77 years to develop the first approved vaccine for Dengue fever. Furthermore, coronaviruses (like Sars Cov-2)  tend not to trigger long-lasting immunity in the people they infect. For example, 25% of Common colds are caused by a human coronavirus but immunity lasts less than a year. Studies suggest that the immunological responses to actual infection with Sars Cov-2 are very variable and can disappear relatively quickly. It has been pointed out that a serious problem with this virus is that it is often unclear who has been infected (we clearly have people who can pass on the disease, who show no or only mild symptoms). The virus, like others of its kind, also undergoes mutations, which could alter the effectiveness of any developed vaccine. It does look as if the unprecedented efforts (these are world-wide and very substantial) to develop safe vaccines, for use in the Covid-19 pandemic, are baring fruit.  However, only an agent that produced relatively long-lasting immunity could eradicate the virus. With or without a vaccine, Sars Cov-2 could be with us for much longer than initially hoped.

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