Detection frequencies and viral load distribution of parvovirus B19 DNA in blood and plasma donations in England.

Abstract

Infections with human parvovirus B19 (B19V) are transmissible by blood components and plasma-derived medicines. The European Pharmacopoeia regulates maximum levels of virus allowed in manufacturers' plasma pools. To evaluate contamination risk prior to re-introduction of UK-sourced plasma for manufacturing, we investigated viraemia frequencies of B19V in plasma samples collected from blood donors before and during COVID-enforced lockdown. Quantitative PCR for B19V DNA was used to screen pools of 96 anonymised plasma samples collected in England from 2017 (n= 29 505), 2020 (n= 3360) and 2021 (n= 43 200). Selected positive pools were resolved into individual samples. Data on donor notifications and related lookback investigations were collected from European countries by on-line survey in 2020. Screening of 76 065 donations identified 80 B19V-positive pools. While most positive samples had low viral loads (<105 IU ml-1 ), primarily from 2017 (77/29 505; 0.3%), two contained high levels of B19V DNA (1.3 × 108 and 6.3 × 106 IU ml-1 ), both likely to contaminate a final manufacturer's pool and lead to discard. The incidence of B19V infection during lockdown was reduced (1/3360 in 2020; 0/43 200 in 2021). Genomic analysis of positive pools resolved to single samples identified B19V genotype 1 in all nine samples. Seroprevalence of anti-B19V IgG antibodies was 75% (143/192). A survey of B19V screening practices in Europe demonstrated considerable variability. Two blood establishments informed infected blood donors of positive B19V results. Information on seroprevalence, incidence and viral loads of B19V viraemia is contributory the evaluation of alternative operational screening strategies for plasma testing.