Half of all donated blood has Covid-19 antibodies

Half of all blood being donated in Kenya has Covid-19 antibodies, a new Ministry of Health report shows.

This means donors were likely to have been infected with coronavirus at some point.

Researchers said they tested blood samples from all six regional transfusion centres between January 3 and March 15. All donors were aged between 16 and 64.

Among the 3,018 samples tested, 44 per cent or 1,333 had Covid-19 antibodies.

The report says based on the seroprevalence, after making some adjustments, it is safe to conclude 48.5 per cent of all Kenyans have already been infected with Covid-19.

The report is part of the surveys being conducted by the ministry and the Kenya Medical Research Institute - Wellcome Trust to estimate the incidence of Covid-19 in Kenya.

“The national estimate of seroprevalence was 48.5 per cent. Seroprevalence varied little by age or sex but was higher in Nairobi (61.8 per cent), and lower in two rural regions," the report says.

The report has been submitted to a scientific journal for peer-review and possible publication.  

"Although high, the estimate is corroborated by other population-specific estimates in the country,” it adds.

The report is available on the online pre-print platform Medrxiv.

The authors suggest Kenya could achieve herd immunity through natural means rather than through vaccination, which has been sluggish and only reached two per cent of the country so far.

“Natural infection is outpacing vaccine delivery in Africa, and this reality needs to be considered as objectives of the vaccine programme are set,” the authors say.

They include Health CASs Rashid Aman and Mercy Mwangangi, acting director general Patrick Amoth, Kadondi Kasera from the ministry and Wangari Ng’ang’a of the Presidential Policy and Strategy Unit.

The World Health Organization says natural infection with Covid-19 could provide similar protection against symptomatic disease as vaccination, at least for six months.

“In most people immune responses remain robust and protective against reinfection for at least six-eight months after infection (the longest follow up with strong scientific evidence is currently approximately eight months),” WHO says in its 'Covid-19 Natural Immunity Scientific brief' published in May.

However, scientists insist vaccination is better because the road to natural immunity leaves many people dead – 3,722 in Kenya by June 11.

Natural immunity also appears to protect people only against the variant that they were infected with, while approved vaccines are effective against most variants.

The Kenya National Blood Transfusion Services says blood with Covid-19 antibodies is safe for transfusion, as no blood-borne coronavirus infections have been reported anywhere in the world.

“Testing of collected blood for Covid-19 is not recommended in the absence of evidence of transfusion transmission or demonstrated infectivity of the Covid-19 virus in blood collected from asymptomatic persons,” KNBTS says in its 'Interim Guidance for Blood Management Intra-Covid-19'. It was published in January.

However, people with active Covid-19 infection in Kenya can only donate blood 28 days after recovery.

KNBTS director Nduku Kilonzo also contributed to the Kemri report.

Others from KNBTS are Evelynn Chege, Christine Yegon, Elizabeth Odhiambo, Thomas Rotich, Irene Orgut and Sammy Kihara.

The Kemri-Wellcome researchers are Sophie Uyoga, Ifedayo Adetifa, Mark Otiende, John Gitonga, Daisy Mugo, James Nyagwange, Henry Karanja, James Tuju, Johnstone Makale, Edwine Barasa, Benjamin Tsofa, Joseph Mwangangi, Philip Bejon, Lynette Ochola-Oyier, George Warimwe, Ambrose Agweyu, Shirine Voller and Anthony Scott.

Others are Christian Bottomley from the London School of Hygiene and Tropical Medicine, and Teresa Lambe and Daniel Wright of Oxford University.

(Edited by Bilha Makokha)