Vitamin D deficiency may impair long

di Filippo L, et al. Endocrine. 2023;doi:10.1007/s12020-023-03481-w.

di Filippo L, et al. Endocrine. 2023;doi:10.1007/s12020-023-03481-w.

Adults with vitamin D deficiency may have lower COVID-19 vaccination antibody levels 9 months after the final vaccine dose compared with those with normal vitamin D levels, according to a brief report published in Endocrine.

“To optimize the long-term response to the vaccine, it may be inferred from our data that it could be better to give it to people who are vitamin D sufficient,” Andrea Giustina, MD, professor of endocrinology at Vita-Salute University San Raffaele in Milan, told Healio. “Therefore, assaying vitamin D and supplementing it if low before vaccination could be suggested. This could allow to reduce the need for frequent booster doses of the vaccine with both clinical and economic implications. Another potential implication of the study is that administering the vaccine in the winter when vitamin D levels are known to decrease in the population could not be ideal.”

Giustina and colleagues conducted a retrospective study of 119 adults who received two doses of the Pfizer-BioNTech vaccine (Comirnaty) from January to February 2021 at a tertiary health care center in Milan (median age, 53 years; 51.3% men). Researchers only included adults who did not have a breakthrough COVID-19 infection after vaccination. Blood samples were collected at the time of the first vaccine dose to measure 25-hydroxyvitamin D levels. Low vitamin D was defined as a 25-(OH)D level of less than 20 ng/mL. Blood samples were tested for the presence of antibodies against the receptor-binding domain of the viral S protein to assess immune response to the vaccine. Antibodies were measured at the time of the first and second doses and 1, 5 and 9 months after the second dose.

Of the study group, 12.6% had obesity and 31% had overweight. The most prevalent comorbidity was a history of hypertension, observed in 16% of participants. The median 25-(OH)D level was 25.6 ng/mL and 24.8% of adults had vitamin D deficiency.

At the time of the second dose, the median antibody level was 42.5 U/mL. At 1 month following the second dose, antibodies peaked at a median of 2,024 U/mL. Antibody levels dropped to 710 U/mL at 5 months and to 507 U/mL at 9 months.

Adults with vitamin D deficiency had lower antibody levels at 9 months compared with those with normal vitamin D levels (346 U/mL vs. 528 U/mL; P = .023). There was a positive correlation between 25-(OH)D level and antibody titers at 9 months (r = 0.32; P = .043). No difference in antibodies was observed between the two groups at any other time point. No differences in immune response were observed among adults with overweight or obesity and those with normal weight, or among adults who smoked compared with nonsmokers.

In multiple linear regression analysis, 25-(OH)D deficiency (beta = –0.35; P = .026) and older age (beta = –0.44; P = .004) were negatively associated with antibody levels at 9 months.

Giustina said further research is needed to address several outstanding questions regarding vitamin D and COVID-19 vaccine response.

“Extending the observation to high-risk populations such as multi-morbid older adults would be important since the impact of low vitamin D on their immune response may be even greater,” Giustina said. “Moreover, checking if the observed effect on antibody levels may translate into a different degree of clinical protection is needed. Finally, the impact of vitamin D supplementation in deficient subjects on the immune response to vaccination should be tested.”

For more information:

Andrea Giustina, MD, can be reached at [email protected].