A specialist in infectious diseases said the global battle for a Covid vaccine could be lost if the virus mutates.
International experts spoke of the challenges to be expected as research into 11 vaccines enters the final phase.
At an event entitled The Global Race for Covid-19 Vaccines, infectious disease specialist Gifty Immanuel warned of the dangers.
“We have come a long way with this pandemic but with progress comes certain pitfalls,” he said.
“Every vaccine has an adverse reaction. All the trials are on a limited population so obviously we do not know the long-term adverse reactions.”
Despite initial results revealing a success rate of up to 95 per cent with some vaccines, Mr Immanuel said this can often drop to 50 per cent once larger groups are immunised and the virus is bound to become resistant.
“The virus right now is having a field day, it is literally feeding on us, but the day you put an effective antiviral vaccine into the system, into the ecology, the virus will fight back and there is a huge probability we might have a vaccine that mutates, like hepatitis B. It a huge area we need to look into,” he said.
“We know this came from animals, recently we have had mink infected. After passage through the mink this particularly furry animal made it much more virulent. Such a comeback could completely destroy what we are planning to obtain in a very heroic manner in such a short span of time.”
Research fellow John-Arne Rottinger told the online seminar, which was hosted by the University of Oxford’s Blavatnik School of Government on Thursday, that more than 200 vaccines have been registered and almost 50 were now in clinical trials.
“The world needs billions of doses and it takes time,” he said.
“Normally it would have taken nearly a year to produce the first lot. It takes time to scale up production and this is why groups have started procuring millions of doses, we have never seen this before.”
The president of the Public Health Foundation of India, Srinath Reddy, said more people urgently need training to be able to administer the vaccines, especially if it needs to be given in two doses.
“We believe 300 million people will be immunised by September next year if the anticipated vaccine programme begins in February,” he said.
“The big challenge will be in the health workforce. Having a trained healthcare workforce is going to be a very important element.
“The real challenge will be finding the people who can deliver the vaccine, we are not only looking at nurses and doctors, but medical and nursing students too.”
Suerie Moon, co-director of the Global Health Centre in Geneva, said lessons need to be learnt from the pandemic.
“It is essential in the future we put money on the table so when the next pandemic hits we are not scrambling in the same way we are today,” she said.
Hours before the lecture, he University of Oxford announced its vaccine had produced promising results in older adults and was ready to move to the final trial stage.