Covid: One vaccine dose can reduce spread of coronavirus by 65% and why this is massively important

Tom Clarke

Former Science Editor

Not only do jabs prevent severe Covid, it stops people contracting the virus in the first place, ITV News Science Editor Tom Clarke reports


What's better than a vaccine that stops you getting seriously ill and dying from Covid-19?

Well, one that stops you getting infected in the first place, therefore preventing coronavirus from spreading. And the great news is, that’s precisely what our Covid vaccines seem to be doing.

Based on clinical trials it was impossible to know how effective new Covid vaccines would be at preventing transmission of the virus. But now lots of people have been vaccinated, researchers at the University of Oxford have shown that just one dose of the Pfizer or AstraZeneca vaccine can reduce spread of the virus by 65%. Even higher with two doses of vaccine.

It’s massively important. Not just because it means our outbreak will be significantly slowed down by vaccination, but also because hopes for some kind of vaccination certificate for travel or entry to certain events have scientific credibility. You can move around knowing you are much less likely to be a risk to others.


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The results of this study come as the latest evidence shows the outbreak in the UK continues to decline. Infection rates in all nations, except Wales, are falling further. (In Wales, infections are the lowest across the board but are now looking to have levelled off.)

According to senior government scientists, this evidence, combined with the new vaccination data, is that cases will continue to fall significantly through next month.

Only then will greater opening up start leading to a rise in infections again. It’s expected those infections will largely be in younger age groups who mix the most and who won’t yet have been vaccinated.


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However, it is expected there won’t be a big surge in cases this summer either.

The combination of the good weather keeping people outdoors and - if all keeps going to plan - vaccination being rolled out to all over-18s by the end of July is expected to keep infections down.

This will of course increase calls for more rapid lifting of restrictions.

However, the vaccine study also revealed five percent of people have a poor immune response after one dose of vaccine. And around five percent of people don’t get a vaccine for one reason or another.

One reason the government and its advisors continue to urge caution is that even once the vaccination programme is complete, millions of adults could still be left with no immunity to Covid.