Lower Vaccine Efficacy Against New COVID-19 Strain Makes Wider Vaccination More Important

With Oxford-AstraZeneca COVID-19 vaccine proving to be less effective in protecting against infections caused by the coronavirus variant found in South Africa, wider vaccination among the general population might be needed to build up herd immunity, public health experts told Sputnik

MOSCOW (UrduPoint News / Sputnik - 09th February, 2021) With Oxford-AstraZeneca COVID-19 vaccine proving to be less effective in protecting against infections caused by the coronavirus variant found in South Africa, wider vaccination among the general population might be needed to build up herd immunity, public health experts told Sputnik.

South Africa halted the rollout of the Oxford-AstraZeneca COVID-19 vaccine in the country on Monday, after a study published by the Wits Vaccines and Infectious Diseases Analytics Research Unit showed the vaccine offered minimal protection against mild-moderate COVID-19 infection from the new coronavirus strain known as the B.1.351 variant first identified in the country in November.

"These early data, which will be submitted for scientific peer-review, appear to confirm the theoretical observation that mutations in the virus seen in South Africa will allow ongoing transmission of the virus in vaccinated populations, as has been recently reported in those with prior infection," the study said.

The study involved approximately 2,000 volunteers where the median age was 31 years old.

If the Oxford-AstraZeneca COVID-19 vaccine failed to reduce transmission of the B.1.351 coronavirus variant among the general population, it raised the question on whether authorities in different countries need to adjust their existing vaccination strategies to deal with this new challenge.

However, lower efficacy of COVID-19 vaccines only makes wider vaccination among the general population more important if we want to protect those who are most vulnerable to COVID-19, public health experts argued.

"We would still need to use the best weapon we have against COVID-19. Lower effectiveness is still better than nothing. The problem is how to roll it out in the most effective way, that is, which groups to target. If the vaccine would prevent at least some infections, it is still justifiable to use it and to require it on certain groups," Alberto Giubilini, a senior research fellow on the Oxford Martin Program on Collective Responsibility for Infectious Disease, told Sputnik.

The expert explained why a less effective vaccine would require more people to be vaccinated to help the general population to reach herd immunity.

"The lower the effectiveness of a vaccine, the stronger the reason for mandating it because you would need higher uptake in order to create the same level of collective immunity that you would have with a more effective vaccine. It is true that the less effective a vaccine, the more difficult it is to realize herd immunity through vaccination. But it is still the case that the more immunity we have, the better," he said.

The South African study on the Oxford-AstraZeneca vaccine could not determine if the vaccine could protect the vaccinated group from more severe complications or death from COVID-19 infections, because the target population were at low risk.

A number of previous studies suggested that almost all existing COVID-19 vaccines, including the Oxford-AstraZeneca vaccine, could help reduce severe symptoms among the vaccinated population, even if they contracted the new coronavirus.

In response to the latest South African study, the World Health Organization (WHO) stressed the importance of finding out whether the Oxford-AstraZeneca vaccine could still help prevent more serious illness among those infected by the B.1.351 coronavirus variant.

"This means it is vitally important now to determine the vaccine's effectiveness when it comes to preventing more severe illness caused by the B.1.351 variant," the WHO said in a statement on Monday.

Even if a vaccine can only help reduce severe symptoms among the vaccinated while not being able to halt transmission of the new coronavirus, such vaccines could still be useful in easing the burden on public health systems in different countries, Giubilini pointed out.

"What counts as a successful vaccine is as much an ethical question as is a scientific one. It depends on what we judge to be 'good enough', and that is an ethical decision. The reason why we are having lockdowns and we are posing this level of harm to young generations is that we have decided we want to prioritize the interests of the elderly and most vulnerable, and to protect health care systems," he said.

The expert explained how such vaccines could allow countries to lift strict lockdowns eventually.

"Preventing severe symptoms and deaths is all that is required to protect such interests. Thus, a vaccine that does that is certainly successful at least at removing the reason we currently consider to justify lockdowns. Some people will still catch the virus, but this is something we need to learn to live with. At some point we will need to decide that a certain level of risk is acceptable. We can't stay in lockdown forever," he said.

In response to the emergence of new COVID-19 variants, such as the ones found in South Africa and the United Kingdom in recent months, other vaccine producers including Pfizer and Moderna have published research results demonstrating that their vaccines remained effective in offering protection against the new variants.

Given the difference in various COVID-19 vaccines, countries could adjust their vaccination campaign in accordance with different vaccines' efficacy to find the perfect balance in protecting different groups in the general population, Giubilini suggested.

"Let's not forget we have different vaccines available which work in different ways. We can pursue different strategies through different vaccines, depending on how effective they are on different groups. For example, we might be able to use a vaccine to reduce transmission on groups more likely to spread the virus (e.g. the young or certain categories of workers) and another vaccine to reduce severe symptoms in the elderly. For example, the Oxford one for the first purpose and the Pfizer one for the second," he said.

Most countries prioritize in offering COVID-19 vaccines to frontline healthcare workers and elderlies who are more vulnerable to infections.

But Giubilini suggested vaccine accessibility might need to be revised based on the how different vaccines work.

"The real problem is identifying the right group to target. For example, if it turns out the vaccine is significantly more effective on young people, not very effective on the elderly, and there is enough availability, you might be able to better protect the elderly by mass vaccinating the young, as that is more likely to create indirect protection for the vulnerable," he said.

Other public health experts proposed alternative strategies, such as targeted lockdowns, in case vaccination alone was not enough to protect the vulnerable groups.

"It is quite possible that vaccination will not sufficiently protect the vulnerable elderly, for a variety of reasons. We need to explore other strategies. One which I have suggested is selective lockdown of the elderly, say over 50-60, while herd immunity is achieved through free social mixing of younger age groups. That would have mortality similar to what we have experienced under the current pattern of lockdowns, but enable younger people to get on with their lives, get the health care system running again, restart the economy etc.," Professor Julian Savulesu, lead researcher of the Oxford Martin Program on Collective Responsibility for Infectious Disease, told Sputnik.

As new COVID-19 variants appeared to be resistance to some existing vaccines, annual vaccinations against possible new variants may become the new norm in the future, the expert suggested.

"COVID -19 is not as bad as Spanish Influenza and probably similar to Asian flu and Hong Kong flu. It will most likely die out in its current form but possibly appear in the future as more virulent form, requiring yearly vaccination, as in flu. It is a numbers game. But in almost all likelihood, we will have to learn to live with COVID as we live with flu, rather than hoping to eliminate it altogether," he said.

Giubilini expressed similar outlooks on how the global COVID-19 pandemic would evolve.

"COVID-19 will not be as banal as the seasonal flu because it is way more lethal. It is a much more serious disease. But we will be able to manage it as we do with the flu: we accept that it exists, it will probably become endemic, and we keep it under control with routine vaccinations," he said.

Based on estimates from Bloomberg's COVID-19 vaccine tracker, it would take more than seven years at today's vaccination rates for countries around the world to vaccinate 75 percent of their populations.