The NHS is calling on Redbridge and Havering residents who have had coronavirus to donate their blood plasma in case it can help others.
NHS Blood and Transplant (NHSBT) is calling on as many donors as possible who caught the virus during the first wave to come forward.
Plasma from people who have recovered from the disease could be transplanted into sufferers to help their bodies fight off the virus.
However, scientists will first have to carry out clinical trials to prove the safety of the treatment, hence the need for new donations.
NHSBT chief medical officer Gail Miflin said: “We need people to offer to donate now so we are ready to potentially provide an additional line of protection during any second wave.
“The number of new infections has declined greatly which is fantastic news. Fewer people are getting Covid-19.
“This does mean we need to work harder to recruit new donors and we urgently need as many people as possible who have recovered to donate, to help us make as much progress as possible now.
“We especially need men who have recovered to donate because they have higher antibody levels. Donating plasma is safe and easy and you could save lives.”
Plasma donation takes about 45 minutes and can be done as often as every two weeks.
The body replaces plasma in less than two days and also quickly replaces antibodies.
Potential donors can call 0300 123 23 23 or visit the www.nhsbt.nhs.uk website.