NHS expected to roll out fourth doses of Covid vaccines but how effective will they be?

People aged 75 and over, those in care homes and those aged 12 and over with a weakened immune system in England will be able to book a fourth dose of either the Pfizer or Moderna vaccine from next week, ITV News understands.

The NHS will be setting out how they’ll be rolled out shortly. 

This is being seen as a precaution by the health authorities principally because many of those in higher risk groups received their booster around six months ago and there are concerns that protection wanes over time. 

“In broad terms the vaccines are very good at preventing serious illness, hospitalisation and death, but they’re less good at preventing infection," Prof Anthony Harnden from the government’s vaccine committee, the JCVI, told ITV News. 

“After two doses this protection against infection dropped after three to four months to offer much lower levels of protection. The booster is also falling off but not quite as sharply. It will also wane after the fourth dose but it might be slower,” he added.

The main role of this particular crop of vaccines is to protect against serious illness and hospitalisation - not infection. The benefit of getting each booster has to be weighted against any potential harms from those extra doses. 

The protection against serious illness also drops slightly over time, he said. 

Different countries are offering different vaccines with different gaps between the doses. A few countries have already started to offer a fourth dose to some groups of people. 

There’s some evidence about the effectiveness of the fourth dose largely from Israel. It became the first country to extend fourth doses to over-60s, healthcare workers and people with weakened immune systems. 

A study from Israel’s Ministry of Health and researchers at several Israeli universities looked at around one million vaccinated people over the age of 60 and suggested a fourth dose of the vaccine offered up to twice the protection against getting infected, and four times the protection against severe illness, compared to those who received three doses.

Because of the study design there are some limitations with the data. 

Yesterday a small trial from Israel was published in the New England Journal of Medicine looking at the effects of the fourth dose of the Pfizer vaccine in younger health care workers in Israel (so not the same group of people who are being offered a fourth dose in England now). The fourth dose boosters were given four months after the third dose. 

The size of the trial plus the short follow up period (only four to five weeks) means interpreting the results needs caution.

“A fourth booster dose does seem to increase protection against infection compared to people who have not had a fourth dose but not dramatically so,” Paul Hunter, professor in Medicine at the University of East Anglia said, adding that it was too early to say the duration of protection.

The authors of the Israeli trial concluded “a fourth vaccination of healthy young health care workers may have only marginal benefits”. 

Some experts say constantly boosting in this way reactively isn’t sustainable in the long term - there are costs to running such a programme. 

Sajid Javid told ITV’s Peston programme that he will wait for the JCVI’s advice before offering more people a second booster or fourth dose, but it’s likely this will happen in the autumn or towards the end of the year. Evidence on the effectiveness of this is still emerging.

But Professor Paul Hunter says that future roll outs of vaccine boosters on an annual or less frequent basis do need to be proven to have value before being implemented.

At the moment the vaccine committees don’t look at cost-effectiveness of the Covid jabs - do they provide good value for what we’re paying for them for the impact they have? - Like they do for other vaccines.

This may change in the future. As may the vaccines that are being offered.

Some are concerned that the current crop of vaccines is providing diminishing returns.

“These two vaccines [Pfizer and Moderna] generate the best response against variants that are no longer in circulation. 

"It’s about time that vaccines caught up with the variants that are currently infecting people, otherwise giving fourth doses might be like old generals fighting old wars,” Dr Simon Clarke, a cellular microbiologist at Reading University, said.