Fourth shot of Covid vaccine is NOT enough to prevent ‘lots of infections’ from Omicron, Israeli study finds
- Fourth dose of the Covid vaccine provides only limited defence against Omicron
- Sheba Hospital, Israel, began administering fourth jab to 270 medical workers
- The trial said the increased antibodies did not prevent the spread of Omicron
- Lead researcher said: ‘For the Omicron variant the vaccine is not good enough’
The fourth dose of the Covid vaccine is less effective on the Omicron variant and provides only limited defence, a preliminary study in Israel has found.
Israel’s Sheba Medical Center began administering a fourth vaccine to more than 270 medical staff last month during a trial program.
Experts studied the defence of the Pfizer booster in 154 people after two weeks and the Moderna booster in 120 people – who had previously been vaccinated three times with the Pfizer vaccine – after one week.
The clinical trial found that both groups showed increases in antibodies ‘slightly higher’ than following the third vaccine last year. But it said the increased antibodies did not prevent the spread of Omicron.
The fourth dose of the Covid vaccine is less effective on the Omicron variant and provides only limited defence, a preliminary study in Israel has found
‘Despite increased antibody levels, the fourth vaccine only offers a partial defense against the virus,’ said Dr. Gili Regev-Yochay, director of the hospital’s infection disease unit. ‘The vaccines, which were more effective against previous variants, offer less protection versus omicron.’
She added: “The vaccine, which was very effective against the previous strains, is less effective against the Omicron strain.
‘We see an increase in antibodies, higher than after the third dose. However, we see many infected with Omicron who received the fourth dose. Granted, a bit less than in the control group, but still a lot of infections.
‘The bottom line is that the vaccine is excellent against the Alpha and Delta [variants], for Omicron it’s not good enough.’
The preliminary results raised questions about Israel’s decision to offer a second booster shot – and fourth overall – to its over-60 population. The government says over 500,000 people have received the second booster in recent weeks.
Dr. Nahman Ash, director of Israel’s Health Ministry, said the research did not mean the fourth vaccine effort was a mistake.
‘It returns the level of antibodies to what it was at the beginning of the third booster. That has great importance, especially among the older population,’ he told Channel 13 TV.
But he said the research would be taken into account as authorities debate whether to expand the additional booster campaign to the broader population.
Israel was one of the first countries last year to widely vaccinate its population and last summer became the first to offer a booster shot. The latest booster campaign for older Israelis also is believed to be the first of its kind in the world.
Figures taken on Sunday night revealed that over 500,000 Israelis have been vaccinated with a fourth dose. Nearly 9.5 million have received at least one dose of the vaccine, and nearly 4.4 million Israelis have received three doses, according to the latest Health Ministry figures.
N’amah Yetzhak Abohaikal, a volunteer with the women’s unit of United Hatzalah emergency service, prepares administer the COVID-19 vaccine to a teen girl as her brother and grandmother watch, at Clalit Health Services in Mevaseret Zion
Israel’s aggressive vaccination efforts have not been able to stop an omicron outbreak in recent weeks. The variant has caused record-setting infection levels and sent a growing number of people to the hospital, though the numbers of seriously ill remain below previous waves.
It has also forced large numbers of Israelis into quarantine, straining schools and businesses.
Omicron is already dominant in many countries and can also infect those who have been vaccinated or had previously been infected by prior versions of the virus. Early studies, however, show it is less likely to cause severe illness than the previous delta variant. Vaccination and a booster still offer strong protection from serious illness, hospitalization and death.
On Tuesday, the Israeli government said it was shortening the mandatory quarantine period from seven days to five days in order to help keep the economy running.
‘This decision will enable us to continue safeguarding public health on the one hand and to keep the economy going at this time on the other, even though it is difficult, so that we can get through this wave safely,’ said Prime Minister Naftali Bennett.
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