Shrinking rate of fresh covid infections creates bizarre problem for vaccine developers

London [UK], June 11 : The shrinking number of new infections in former coronavirus hot spots, including Britain, China and many of the hardest-hit regions in the United States, may be a good news, of course, but researchers who are rushing to develop vaccines in a global race to ward off the contagion may have to face a bigger problem with less people to test drugs.
A lead researcher from Oxford University group, one of the furthest ahead with human trials, admitted to The Washington Post that the declining numbers of new infections this summer could be one of the big hurdles vaccine developers face in the global race to beat down the virus.
Vaccine developers need sufficient numbers of infected people, with and without symptoms, circulating in the general population -- in the streets, workplaces, clinics -- to test whether the vaccine protects volunteers when they are exposed.
If there is not much chance of volunteers running into someone with the virus, researchers will have to expand their efforts and potentially chase down outbreaks in other countries, delaying the prospect of a successful vaccine.
Pascal Soriot, chief executive of AstraZeneca -- a British-Swedish firm that has partnered with the varsity group and gotten an infusion of USD1.2 billion from the US government to develop its vaccine -- was quoted as saying in a recent briefing that the trajectory of transmissions added a new sort of time pressure.
"Now the problem we will all have, I think, is we are running against time a little bit, because we see already the disease in Europe is declining," Soriot told the Post.
"Pretty soon, the disease's intensity will be low and it will become difficult" to gauge efficacy in a vaccine trial.
Adrian Hill, director of the Jenner Institute at Oxford and a co-leader of the Oxford effort, said, "We're in the bizarre position of wanting covid to stay, at least for a little while. But cases are declining."
For instance in the United States, the Trump administration has pledged to pursue a vaccine at "warp speed," plugging the possibility of having something ready by the end of the year. That would be an unprecedented feat, as vaccines in the past have taken years or decades to bring to market.
Getting approval for use in the United States will require large-scale trials conducted over several months -- long enough for researchers to observe whether people randomly assigned to receive the experimental vaccine are getting sick significantly less often than people who get a placebo.
Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, said the trials will involve 30,000 volunteers, and, to assess how well a vaccine is working, scientists will need to see at least 100 of those volunteers get sick. If there's not much virus around, hitting that target might be tough.
But he too acknowledged that the trials being planned depend on the virus staying in circulation.
Stuck amid such a situation, researchers may have to get creative to find the outbreaks they need, the media reported further.
And so the Oxford trial is focusing its volunteer recruitment effort on British health-care workers, "as they have the highest rates of virus infections," said Sarah Gilbert, a leader of the group.
Gilbert suggested that as lockdown measures are eased, transmission in Britain may rise again, providing more opportunity to test the vaccine as people move around in their day-to-day lives. But other countries in Europe have so far seen no spikes since loosening their lockdowns.
If case infections continue to decline, the Oxford scientists are also looking beyond Britain and Europe for trial sites. They got approval last week from the health regulator of Brazil, where the virus continues to surge, to conduct a trial there involving 2,000 volunteers.
Fauci said sites in Brazil and South Africa may be considered for US-led trials.
"I think you're going to have go with where the dynamics of the outbreak are, and that changes. You really have to be mobile and flexible," Fauci was quoted as saying.