‘A 3-month gap between two AstraZeneca doses gives better protection’

TIMES evoke

‘A 3-month gap between two AstraZeneca doses gives better protection’

19.05.2021

Scientist Andrew Pollard co-developed the AstraZeneca vaccination together with Sarah Gilbert at Oxford University. Speaking to Srijana Mitra Das at Times Evoke, Pollard, head of the Oxford Vaccine Group, shares insights around the Covid-19 vaccination:

Both India and the UK recently changed the interval between two AstraZeneca doses. What is the ideal time gap?

We have very good data showing strong protection for the first three months between the two doses. A three-month interval produces very good protection – this gets even better with a longer interval from three to four months. A longer time gap gets a stronger immune response after the second dose.

The reason for the UK’s change is the situation posed by the B.1.617 variant and the attempt to improve immunity and curb transmission. But to get the maximum immune response, it’s worth waiting longer. There is a trade-off between getting a high response earlier or waiting longer and getting an even better immune response.

Could you address fears over AstraZeneca and blood clots? And why do diverse countriesrecommenddifferent age restrictions for your vaccine?

The biggest problem the world is facing now is the Covid-19 virus killing millions of people, with many more expected to succumb in the current waves. If we do a comparison between the risk of the virus and a very rare type of blood clot, the possibility of the latter happening is extremely low – the possibility of being affected by Covid-19 is high.

If you’re in a region where the disease is widespread, it’s much better to be vaccinated with a very, very small risk at all. If you’re in a part of the world where there are plenty of vaccines and almost no disease, the trade-offs are different. The diverse age restrictions in different countries are because they’re in the fortunate position of having most people vaccinated and very low rates of disease.

How effective is AstraZeneca against emerging variants?

The virus will generate variants as long as there is transmission. We’re a long way from vaccinating the world’s population, so we will see many variants evolving. However, we are optimistic that the current generation of vaccines will have a huge impact in improving immunity in vaccinated groups, so most people are protected against severe disease, hospitalisation and loss of life.

Can AstraZeneca be used eventually to vaccinate children?

There is very little good quality evidence at the moment about any change in the severity of the disease affecting children. We have not seen that in most populations – this is a very unusual and rare phenomenon as of now. For that reason, given how few adults worldwide have been vaccinated, we must focus the available doses on individuals most likely to be severely affected. My view is that highrisk people must be vaccinated before we start vaccinating children, who are still at low risk. The existing data on this is consistent throughout the pandemic – the rate of severe disease for children is low. The greater risk is for older adults and people with health conditions. Focus all available vaccines on them.

What are your views on vaccine equity?

We are all part of the human family – the value of a life in a rich country should be the same as a life in a poorer country. Morally, we should be distributing vaccines with equity. However, there is also a pragmatic reason for rich countries to do this – the virus will mutate and disrupt the global economy more if we don’t vaccinate the vulnerable in all countries. So, there are moral, health and economic security reasons for vaccine equity.

At the university, we are very firm on vaccine equity – one of the approaches we’ve taken in our partnership with Astra-Zeneca is to develop a distributed network of over 20 manufacturing sites around the world to maximise production, so the vaccine can be made and supplied to all countries at the fastest possible. That is our university’s goal – our work is not for profit and that is the nature of our partnership with Astra-Zeneca.

What lessons have been learned from the pandemic so far?

We need good surveillance systems to pick up disease threats earlier. We also didn’t have adequate capacity in most countries to produce enough personal protective equipment and diagnostic tests. We must have more security around healthcare staff and stronger disease surveillance and monitoring.

Alongside, the world has done remarkably well in vaccine development, with 15 vaccines in total authorised in at least one country. That’s when we’re only a year on – that’s a huge success where normally, vaccines take around10 years to develop.

I hope the biggest legacy from the pandemic will be an improved public understanding of the value of science – as the new generation grows up with greater respect for science, they will become our leaders one day and will shape better public policy, based on evidence.

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This (protection) gets even better with a longer interval from three to four months. A longer time gap gets a stronger immune response after the second dose The existing data is consistent throughout the pandemic – the rate of severe disease for children is low. The greater risk is for older adults and people with health conditions. Focus all available vaccines on them

At the university, we are very firm on vaccine equity... our work is not for profit and that is the nature of our partnership with AstraZeneca