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Study investigates chronic health conditions and COVID antibody response after second jab

After a second vaccination, a real-world analysis showed that a quarter of those with chronic health conditions had no detectable COVID antibodies.

Vaccination against COVID-19 is critical to controlling the pandemic. Although the currently available vaccines, are very effective, it is still possible to become infected after receiving both vaccination doses. In the US, for instance, the Centers for Disease Control and Prevention, reported in May 2021, that there had been 10,262 COVID-19 vaccine breakthrough infections. These occurred in patients with a median age of 58 years and while 10% of these patients were hospitalised, fortunately only 2% died. Furthermore, in a recently published study among 1497 healthcare workers, 39 experienced a breakthrough infection and around the time of infection, neutralising antibody levels were found to be lower than in matched, uninfected control workers. Other evidence points to a reduced antibody response to vaccination among solid organ transplant recipients. With an apparent lack of data on how underlying chronic health conditions impact on antibody response, a team from the Department of Medicine, National Jewish Health, Denver, US, decided to examine the real-world antibody response among vaccine recipients with a range of underlying chronic health problems. The team used the National Jewish Health electronic medical records to identify those who were fully vaccinated and had spike IgG antibody readings done at least 14 days after the second dose. These results were considered as either positive or negative and the team used multivariate logistic regression analysis to identify any clinical characteristics associated with negative spike IgG antibody levels.

The researchers identified 226 patients with a mean age of 62 years (62% female), of whom 66% had been fully vaccinated with BNT162b and the remainder, mRNA-1273. After a mean of 62 days, just over a quarter (26%) of all patients had no detectable levels of COVID-19 antibodies, 47 given BNT162b and 11 mRNA-1273. The proportion testing negative varied considerably depending on the chronic health condition. For example, 14% of those with chronic obstructive pulmonary disease tested negative, 29% with diabetes, 46% with interstitial lung disease and the highest level, at 53%, was found in those with congestive heart failure. Using regression analysis, the authors calculated that the presence of interstitial lung disease was a significant risk factor for a negative antibody response (odds ratio, OR = 0.21, 95% CI 0.08–0.56), as was congestive heart failure (OR = 0.26) and the use of biologics or Janus kinase inhibitor drugs (OR = 0.17). Interestingly, there was no significant impact from other medicines such as systemic corticosteroids and immunosuppressants such as methotrexate, mycophenolate, azathioprine and tacrolimus.

The authors discussed that though it is widely accepted that no vaccine offers complete protection against infection, their study has raised concerns that among a proportion of patients with chronic health conditions, the absence of detectable antibodies could indicate that such individuals have no protection and are therefore at risk of breakthrough infections. Nevertheless, they also noted that to date, there have been no infections in these patients and that it is possible that an immune response could still be possible. They called for further studies of immunologic response to define ongoing COVID-19 risk in such patients.

Liao SY et al. Impaired SARS-CoV-2 mRNA vaccine antibody response in chronic medical conditions: a real-world data analysis. MedRxiv 2021