Thursday, October 21

Vaccines have given us hope, but they will not end the global battle against Covid | Andrew Pollard | Opinion


AAfter a difficult year of battling Covid-19, we are now starting to see many effective vaccines launched around the world, including the Oxford / AstraZeneca vaccine, which I helped develop. So, hopefully, people begin to ask themselves, “When will life return to normal?”

The main indication of this will be when the pressure begins to ease on public health systems. So far the signs are good, as shown by almost all Oxford / AstraZeneca, Johnson & Johnson, Novavax, Moderna and Pfizer / BioNTech vaccines. complete protection against hospitalization, even in countries with new variants.

This is still great news, but it is tempered by the fact that we have so many vulnerable unvaccinated populations around the world. We urgently need to distribute vaccines to prevent serious diseases. We, and our politicians, must break down barriers to distribution rather than lift them.

This is especially pertinent as we have seen the emergence of new variants. These mutations appear to have arisen in populations where a high proportion of individuals have been infected and a reasonably high level of background immunity already exists, so the virus had to change to survive.

The mutations we are seeing in South Africa and Brazil specifically make it easier for the virus to infect people who are already immune by evading the neutralizing antibodies that humans produce after natural infections or vaccinations.

Despite this troubling observation, there should be some optimism that immunity to the virus from vaccines or post-infection could prevent serious disease, even as the spread continues. After all, the virus is not here to kill us. Its reason for being is to spread, and it needs us alive to do better.

In fact, the immune system is very complex and other important functions are preserved even with variants that can prevent neutralization of antibodies. In response to infection and vaccination, most people produce strong T-cell responses (important for controlling the infection once it begins) and other types of binding antibodies (which can attack infected cells and kill them). These T cells and binding antibodies can play an important role in preventing serious disease and should be little affected by the mutations we are seeing.

However, continued transmission of new variants is likely to occur in both naturally infected and vaccinated populations in the coming years. The new mutations allow a continuous infection in the nose and throat so that the virus can survive. Coronaviruses are very common in humans and almost all of us will have had coronavirus infections in childhood, but we still re-infect ourselves and develop “colds” with them throughout our lives. This is a very likely future pattern for the pandemic coronavirus.

We need to understand if this thesis is correct, as it will tell us how best to respond to the virus as it changes. Due to the virus’s ability to mutate, we may have to find ways to adapt to living with it as it continues to spread in the population, leading to mild symptoms of upper respiratory infections in most and more serious illnesses. among the small population of people with this disease they are not immune or whose immunity is waning.

If this proportion is small, it may be manageable by health systems such as the NHS, as is the case with seasonal influenza. We may need updated vaccines annually to monitor changes in the virus or waning immunity over time.

If protection against serious diseases and hospitalization can be maintained in the future through the current generation of vaccines, we could well have contained the problem of pressures on our health systems, and the end of the pandemic, in that sense , it could be in sight.

As we assess the real-world impact of current vaccines versus hospital admissions, developers are already working on next-generation vaccines, aimed at better controlling new variants, should they become necessary.

There is definitely cause for hope, but this is not the time to become complacent.

  • Andrew Pollard is Director of the Oxford Vaccine Group at Oxford University and principal investigator of the ChAdOx1 nCoV-19 coronavirus vaccine trial, which now collects data from nearly 24,000 volunteers in the UK, Brazil and South Africa.

The fee for this item has been donated to charities.


www.theguardian.com

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