Details

Autor(en) / Beteiligte

• Kolarić, Branko
• Ambriović-Ristov, Andreja
• Tabain, Irena
• Vilibić-Čavlek, Tatjana

Titel

Waning immunity six months after BioNTech/Pfizer COVID-19 vaccination among nursing home residents in Zagreb, Croatia

Ist Teil von

• Croatian medical journal, 2021-12, Vol.62 (6), p.630-633

Ort / Verlag

Croatia: Sveuciliste U Zagrebu

Erscheinungsjahr

2021

Quelle

MEDLINE

Beschreibungen/Notizen

• To assess the humoral immunity to COVID-19 in nursing home residents six months after vaccination. This seroepidemiological research enrolled 118 residents of one nursing home in Zagreb. All participants received two doses of BioNTech/Pfizer COVID-19 and had no previously detected SARS-CoV-2 infection. The samples were tested for the presence of neutralizing antibodies using a virus neutralization test. A SARS-CoV-2 strain isolated in Vero E6 cells from a Croatian COVID-19 patient was used as a stock virus. Neutralizing antibody titer was defined as the reciprocal of the highest serum dilution that showed at least 50% neutralization. Neutralizing antibody titer ≥8 was considered positive. Sixty-four (54%) participants had a positive neutralizing antibody titer, 27 (23%) had a low positive titer (titer 8), and 27 (23%) had a negative titer. Women had a significantly higher median titer than men (16 [interquartile range, IQR 24] vs 8 [IQR 12], Mann-Whitney U=1033, P=0.003). Age was negatively but not significantly correlated with neutralizing antibody titer (Spearman's rho -0.132, P=0.155). Almost half of the participants (46%) had a negative or low positive titer six months after having been fully vaccinated. This study suggests that humoral immunity among nursing home residents considerably wanes six months after BioNTech/Pfizer COVID-19 vaccination. Our results could contribute to the discussion about the need for a booster dose.