Researchers with Oxford University Hospitals NHS Foundation Trust have found antibody responses to COVID-19 decrease by half in less than 90 days. The report published this month, ‘The duration, dynamics and determinants of SARS-CoV-2 antibody responses in individual healthcare workers,’ revealed that antibody levels peak lower and fall faster in younger adults.
Additionally, antibodies to the virus last longer in those who have experienced symptoms and lose their strength faster in those who are asymptomatic. The study found that “increasing age, Asian ethnicity, and prior self-reported systems were independently associated with higher maximum antibody levels”.
The ongoing study of antibody levels in staff members at Oxford University Hospitals NHS is a collaboration between Oxford University Hospitals and Oxford University, with support from the NIHR Oxford Biomedical Research Centre. The report presents six months of data from a study of over 3,000 Oxford University Hospital workers who have been tested more than once for antibodies.
Those who tested positive were asked to take part in further research to understand their immunity to the virus. They were among the almost 10,000 staff who were tested for presence of COVID-19 and antibodies to the virus.
While there have been many reports on COVID-19 in healthcare workers, this ongoing study is the first to comprehensively investigate all staff groups across an institution and combine data from both symptomatic and asymptomatic staff testing programs. Researchers conclude that further research will be required to track the long-term duration of antibody levels and their association with COVID immunity.
The findings will likely influence the approach of governments and businesses to post-lockdown life in the period between the release and widespread distribution of a vaccine.
The data will also be used by Professor Sarah Walker at Oxford University who currently works with the Office for National Statistics on the COVID-19 Infection Survey to provide the United Kingdom with the most accurate incidence and prevalence data.
Professor David Stuart told Cherwell: “Our recent work is an important part of understanding how long antibodies last. However immunity to infection is multifactorial and so even if antibodies fall it is possible that immune memory and other cellular immunity may still provide some protection.
“This is something we will be able to study over the coming months. It will obviously be important too to understand how long protection following vaccination lasts, which may be different to responses to infection.”
The investigation showed antibodies faded faster in young adults and those who are asymptomatic, however, the reasons for this are not yet known.
Stuart added: “For asymptomatic individuals it is possible to hypothesise that as the original exposure was less significant the original responses may be weaker. It is interesting but not yet explained why levels fell faster in young adults.”
Image credit: Felipe Esquivel Reed, Wikimedia Commons