THL´s study: Third dose of COVID-19 vaccine produces significant antibody levels against all viral variants in working-age subjects
According to a new study by Finnish Institute for Health and Welfare (THL), the level of antibodies was high both one and two months after vaccination in working-age people who received a third dose of the vaccine as a booster dose. Antibodies were found against all viral variants studied, i.e., delta, beta, and omicron variants.
The THL study evaluated immune responses to the third vaccine dose in twenty adults aged 27 to 63 years and in nine nursing home residents aged 71 to 89 years (1). Both Moderna´s Spikevax and BioNTech Pfizer's Comirnaty were studied.
Subjects had received the third dose of vaccine 6-9 months after the second dose. Antibodies were measured from samples taken 1-2 months after the booster dose.
In the elderly, the level of antibodies was, on average, lower than in the younger subjects, and was not sufficient in all subjects to neutralize the omicron and beta variants in laboratory experiments.
“The booster vaccine has been shown in previous studies to produce a 2- to 7-fold increase in antibody response compared to a second dose. The strength of the response is affected by the age of the vaccinees, the vaccine preparation, the interval between vaccine doses, and the methods used to measure the antibodies, ”says THL research manager Merit Melin.
Spikevax produces a strong immune response and is a recommended booster vaccine, especially for the elderly
A small proportion of the working age subjects had received a booster dose of Spikevax and had higher levels of antibodies than those who had received Comirnaty.
Spikevax has previously been shown to produce more than twice the level of antibodies compared with Comirnaty in adults receiving two doses of vaccine (2). The antibody concentration was the higher the younger the subjects.
Similarly, the efficacy of vaccines against infections and severe disease caused by alpha- and deltavariants has been found to remain somewhat better with two doses of Spikevax compared with those vaccinated with Comirnaty (3).
"Spikevax should be used for third doses, especially in the elderly, as it appears to produce a stronger immune response," says, THL chief physician Hanna Nohynek.
Antibody levels following the booster vaccine have been reported previously in an English study published in December (4). The study compared immune responses after booster vaccination with seven different covid-19 vaccines, of which the mRNA vaccines produced the strongest antibody response.
The omicron variant is able to evade antibody-mediated protection against infection, as not all antibodies produced by vaccination recognize the structures of the altered spike protein.
“Previous studies have shown that the level of antibodies induced by two doses of the vaccine is not high enough to effectively neutralize the omicron variant, although those vaccinated at the extended dose interval may be in a slightly better position,” says Melin (5).
The third dose of the vaccine raises the level of antibodies to a higher level, which is also sufficient to neutralize the omicron variant. The duration of protection against infection depends on how long the antibodies remain at a sufficiently high level.
"These results emphasize the importance of the third dose of vaccination now that we aim to slow down the spread of the omicron variant in Finland also by vaccinations," says Nohynek.
References
1. Haveri et al: Neutralizing antibodies to SARS-CoV-2 Omicron variant after 3rd mRNA vaccination in health care workers and elderly subjects and response to a single dose in previously infected adults. medRxiv 2021. https://www.medrxiv.org/content/10.1101/2021.12.22.21268273v1.
2. Steenselds et al.: Comparison of SARS-CoV-2 Antibody Response Following Vaccination With BNT162b2 and mRNA-1273. JAMA 2021. https://jamanetwork.com/journals/jama/fullarticle/2783797
3. Dickerman et al.:Comparative Effectiveness of BNT162b2 and mRNA-1273 Vaccines in U.S. Veterans. The New England Journal of Medicine 2021. https://www.nejm.org/doi/full/10.1056/NEJMoa2115463
4. Munro et al.: Safety and immunogenicity of seven COVID-19 vaccines as a third dose (booster) following two doses of ChAdOx1 nCov-19 or BNT162b2 in the UK (COV-BOOST): a blinded, multicentre, randomised, controlled, phase 2 trial. The Lancet 2021. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02717-3/fulltext
5. Dejnirattisai et al.: Reduced neutralisation of SARS-CoV-2 omicron B.1.1.529 variant by post-immunisation serum. The Lancet 2021. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02844-0/fulltext
Further information
Hanna Nohynek
Head Physician
THL
[email protected]
Merit Melin
Research Manager
THL
[email protected]
The press release updated on 29 December at 14.03: the first link added to the lisf to references.
