The good news about Covid-19 boosters and the fourth dose

Evidence is mounting that the protection offered by Covid booster doses wanes but experts reveal why it doesn’t mean you’ll need a fourth jab.

Healthy people may not need a fourth dose of the Covid-19 jab for years — if ever.

While the effectiveness of booster vaccines at preventing infection begins to wane 10 weeks after the shot, new research shows most of us will still have built sufficient immunity to fight the virus off in a few days.

The studies, published in the last month, say it is unlikely most people who have had a third vaccine would end up in hospital or die.

But the situation is different for the elderly and the immunocompromised.

The UK, Israel and other countries are already dispensing fourth vaccine doses to this group and Australia’s expert Australian Technical Advisory Group on Immunisation last month recommended those people receive a fourth dose three months after their third.

“I think for most of us in the short term a fourth vaccine is certainly unnecessary,” University of Newcastle immunologist Associate Professor Nathan Bartlett said.

“We’ll all been immunised three times, many of us have also been infected.

“So the vast majority of us have quite robust immunity now, which will almost certainly keep us hospital and there’s no immediate need to boost that.

Fourth Covid vaccine unlikely to be needed by healthy people. Picture: NCA NewsWire / David Crosling

“The fourth vaccine has to have a very different messaging around it. And this is far more about personal choice and understanding the risks that you face in disease and infection rather than being population-wide.”

Immunity to other coronaviruses that cause the common cold appeared to last for at least two to three years after infection, he said.

“What we hope will happen with Covid is it’ll become the same, it’ll be a virus that has some level of immunity to protect for a number of years and if we do get some breakthrough infection, it’s very mild, it’s a cold,” he said.

Researchers found immune cells against the SARS coronavirus, which killed nearly 800 people in a 2003, lasted for more than 17 years.

University of Washington research has found immune cells against the virus that causes Covid continue to mature well after vaccination and the antibodies they produce keep gaining the ability to recognise new variants.

The antibodies our bodies produce six months after vaccination are more potent than the one produced one month after the jab, they reported.

The US Centres for Disease Control found vaccine effectiveness against hospitalisation with Covid was 91 per cent two months after a third dose but is still strong at 78 per cent by the fourth month after a third dose.

UK research determined that among the vaccinated, protection against hospitalisation is 90 per cent after a third Pfizer booster dose and is still 75 per cent 10-14 weeks after the jab.

A Moderna booster provides 90-95 per cent protection against hospitalisation nine weeks after the jab.

Originally published as The good news about Covid-19 boosters and the fourth dose