Longer intervals between COVID-19 vaccine doses produce higher antibody levels
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LISBON, Portugal — A study conducted among health care workers in the United Kingdom demonstrated that longer intervals between COVID-19 vaccine doses produced higher antibody levels, researchers reported here.
“We’ve also shown that in those with previous infection, timing between exposure and vaccination plays a critical role in post-vaccination antibody responses,” Ashley D. Otter, PhD, technical lead for SARS-CoV-2 serology at the United Kingdom Health Security Agency, said in a press release.
Otter and colleagues measured antibody levels in blood samples from 5,871 health care workers in the U.K. who received the Pfizer-BioNTech vaccine. Among them, 3,989 had received one dose and 1,882 had received a two-dose series.
Among participants who had never been infected with SARS-CoV-2, geometric mean anti-S titers following the first dose were 75.48 binding antibody units/mL, the researchers reported. After the second dose, this increased to 7,049.76 BAU/mL. Participants with a prior SARS-CoV-2 infection had even greater levels of protection —2,111.08 BAU/mL after one dose and 6,052.39 BAU/mL after two doses.
A longer time between infection and vaccination was associated with increased antibody levels, from 1,970.83 BAU/ml (95% CI, 1,506.01-2,579.1) 3 months after infection to 13,759.31 (95% CI, 8,097.78-23,379.09) 9 months after infection.
A longer period between doses also was associated with higher antibody levels — up to nine times higher [2 to 4 weeks = 1,268.72 (95% CI, 1,043.25-1,542.91); more than 10 weeks = 11,479.73 (95% CI, 10,742-12,267.24)].
“This study shows that a longer time between vaccine dose 1 and dose 2 results in higher antibody responses in naive participants, which strongly supports the decision by the U.K.’s Joint Committee on Vaccination and Immunization and the U.K. government to lengthen the interval between vaccine doses,” Otter said.
Perspective
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This study provides more evidence that the 3-to-4-week dosing interval used for COVID-19 messenger RNA vaccines was suboptimal.
Spacing the doses not only would have stretched supply in the early days, but it would’ve led to increased immunity as well as less waning, providing less of an impetus for boosters.
The study also shows that those individuals with prior infection likely need only one dose of the two-dose vaccines for sufficient protection. Hopefully, this study should be incorporated into revised recommendations for optimal does intervals.
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Otter AD, et al. Abstract 03757. Presented at: European Congress of Clinical Microbiology and Infectious Diseases; April 23-26, 2022; Lisbon, Portugal (hybrid meeting).
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