Safety of measles, rubella and mumps vaccines in adults: a prospective cohort study

The third dose of measles-containing vaccine induces robust immune responses against measles in young seronegative healthcare workers who had previous two-dose measles vaccination

BACKGROUND

Despite the low measles antibody positivity rate among young healthcare workers (HCWs) who have previously received two doses of a measles-containing vaccine (MCV), whether an additional dose of MCV acts as a booster remains unknown. Thus, we aimed to evaluate the immune responses to a third dose of MCV in young HCWs.

METHODS

Hospital-wide measles seroprevalence was assessed using enzyme-linked immunosorbent assay (ELISA). The immunogenicity of a third dose of MCV was determined in young seronegative HCWs (born between 1986 and 1997) who had previously received a two-dose measles vaccination.

RESULTS

A total of 3033 (92.6%) HCWs had anti-measles immunoglobulin G. The lowest seropositivity rate was observed in HCWs aged 20-24 years (87.7%). In this group, HCWs who received a third dose of MCV had higher seropositivity than those who received a second dose (89.5% vs. 75.4%). A third dose of MCV was administered to 18 HCWs who did not have anti-measles IgG despite two doses. Neutralizing antibody titers increased significantly 4 weeks after the third vaccination. Although neutralizing antibody titers decreased 1 year post vaccination, 17 (94.4%) HCWs had medium (121-900 mIU/mL) or high (>900 mIU/mL) levels. Furthermore, the third dose of MCV increased the measles virus-specific T-cell effector function.

CONCLUSIONS

The third dose of MCV induced a strong immune response against measles in young seronegative HCWs who had previously received a two-dose measles vaccination.

SARS-CoV-2 spike IgG titres up to 137 days following Comirnaty mRNA COVID-19 vaccination, Israel, February to May 2021

Background

Data regarding the long-term protection afforded by vaccination for the SARS-CoV-2 infection are essential for allocation of scarce vaccination resources worldwide.

Methods

We conducted a retrospective cohort study aimed at studying the kinetics of IgG antibodies against SARS-CoV-2 in COVID-19-naïve patients fully vaccinated with two doses of Comirnaty mRNA COVID-19 vaccine. Geometric mean concentrations (GMCs) of antibody levels were reported. Linear models were used to assess antibody levels after full vaccination and their decline over time.

Results

The study included 4,740 patients and 5,719 serological tests. Unadjusted GMCs peaked 28–41 days after the first dose at 10,174 AU/mL (95% CI: 9,211–11,237) and gradually decreased but remained well above the positivity cut-off. After adjusting for baseline characteristics and repeated measurements, the antibodies half-life time was 34.1 days (95% CI: 33.1–35.2), and females aged 16–39 years with no comorbidities had antibody levels of 20,613 AU/mL (95% CI: 18,526–22,934) on day 28 post-first-dose. Antibody levels were lower among males (0.736 of the level measured in females; 95% CI: 0.672–0.806), people aged 40–59 (0.729; 95% CI: 0.649–0.818) and ≥ 60 years (0.452; 95% CI: 0.398–0.513), and patients having haematological (0.241; 95% CI: 0.190–0.306) or solid malignancies (0.757; 95% CI: 0.650–0.881), chronic kidney disease with glomerular filtration rate (GFR) ≥ 30 (0.434; 95% CI: 0.354–0.532) or with GFR < 30 mL/min (0.176; 95% CI: 0.109–0.287), and immunosuppression (0.273; 95% CI: 0.235–0.317). Body mass index, cardiovascular disease, congestive heart failure, chronic obstructive pulmonary disease, diabetes and inflammatory bowel diseases were not associated with antibody levels.

Conclusions

Vaccination with two doses resulted in persistently high levels of antibodies (≥ cut-off of 50 AU/mL) up to 137 days post-first-dose. Risk factors for lower antibody levels were identified.