4th Dose COVID Vaccination Booster (April 11th 2022 update)
- 2 doses of mRNA vaccine are extremely protective against death and severe disease as evidenced by data from Hong Kong from the latest Omicron wave.
- The unvaccinated were 21 times more likely than patients with 2 or 3 doses to die or get severe disease.
- It is unclear if a 4th vaccination dose is currently needed for immune competent individuals.
- An Israeli study published April 5, 2022 suggested while a 4th dose could reduce the probability of infection it did not in fact significantly improve protection against severe disease despite the conclusion of the authors.
- This was a retrospective cohort study.
- The study was confounded by the fact that 3-dose recipients were more likely to be from a poorer, Arab population whereas most 4-dose recipients were from a wealthier, Jewish population.
- Subjects were only followed for 40 days after the 4th dose.
- On March 29, 2022, the CDC suggested a 4th vaccination for people over the age of 50, and immunocompromised patients more than 4 months from their 3rd vaccination.
- This is in contrast to the European Center for Disease Prevention and control that made the following statement on April 6th: “For immunocompetent individuals below 60 years of age, the administration of a second booster dose is not supported by the available data on continued level of vaccine protection against severe disease or death.”
- A 4th dose is able to increase antibody levels substantially but these wane quite quickly. It does not currently appears that T cell based immunity against severe disease is significantly improved with a 4th dose of vaccine.
- Link to current CDC vaccination recommendations
tom f. - April 27, 2022 12:00 PM