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Coronavirus Disease 2019

Effectiveness of the Fourth Dose Against COVID-19: New Data

The fourth dose of vaccination has some new data to back it up.

Key points

  • People now face the question of whether to get the fourth dose of vaccination.
  • Data from Israel and the UK indicated that a third booster dose of one of the mRNA vaccines sharply lowers the likelihood of catching SARS-CoV-2.
  • New data provide support for the effectiveness of the fourth dose of the mRNA vaccine.
  • Many people worry that wealthy countries will rush to offer more boosters to fight Omicron and exacerbate the global vaccine disparity.
Israeli Health Ministry
Effectiveness of the Fourth Dose
Source: Israeli Health Ministry

Many people now face the question of whether to get the fourth dose of vaccination. Recent reports even show that despite the CDC directive, many pharmacies refuse to give fourth shots to immune-compromised patients. Yet, new data suggest the fourth dose is effective and may be life-saving for many.

Already in late last year, Nature News published a summary of studies showing that the third dose (booster) shot of anti-COVID-19 vaccination provides extra protection. Data from Israel and the UK indicated that a booster dose of one of the mRNA vaccines sharply lowers the likelihood of catching SARS-CoV-2.

Following these studies, public health officials across the world urged all adults to get a booster dose of vaccine. Variant specific top-ups are also in the making, but doctors worldwide recommend not to wait and take available shots today as these boosters could help fight the surge of Omicron infections.

Based on the United States' national estimates, researchers found that a broad booster such as the third dose could decrease the virus’s reproduction number by around 30 percent.

While the third dose is the widely accepted recommendation now, it is important to note that many researchers oppose it due to debates over equity and the prioritization of limited vaccine resources. Many people worry that wealthy countries will rush to offer more boosters to fight Omicron and exacerbate the global vaccine disparity. It is not only a matter of equity, as some researchers say there is a chance that this exact disparity contributed to Omicron’s emergence and rapid spread, to begin with.

Effectiveness of the Fourth Dose: New Findings

Still, a fourth booster is in play, and new, preliminary data show it is effective against severe symptoms. Data from Israel, collected by the Ministry of Health, Weizmann Institute of Science, the Technion, the Hebrew University, and Gertner Institute in Sheba Medical Center, show that the fourth dose raises protection against infection by up to two times, compared to those previously-vaccinated with the third dose.

Moreover, after 12 days since the fourth dose, protection against severe illness was raised by up to three times and higher, as shown in the illustration above, compared to those previously-vaccinated with the third dose.

The analysis is based on the data of about 400,000 adults aged 60 and older vaccinated with the fourth dose compared with about 600,000 adults aged 60 and older vaccinated with the third dose. Researchers accounted for gender, ethnicity, date of exposure, and more. The researchers used similar methods to those they used in their earlier publication on the results of the third dose, published in the New England Journal of Medicine.

Indeed, questions continue over how much boosters will help in the long run and how often they will be needed. The Omicron variant has heightened the debate over their role, in particular. A statement released on January 11th, 2022, by the World Health Organization warned that “a vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be appropriate or sustainable.”

While the debate over the fourth dose continues, we need to be aware of reliable and trustworthy data on the issue and use protection measures as much as needed with the hope we will know better days soon.

Israeli Health Ministry
Effectiveness of the Fourth Dose
Source: Israeli Health Ministry
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