Several different vaccines manufactured at dozens of sites globally will be needed to provide an effective defence against Covid-19, scientists have said.
Experts from the University of Oxford, Harvard Medical School and the Gamaleya National Research Centre in Russia shared their experiences at an online conference hosted by Saudi Arabia.
Researchers behind the Oxford-AstraZeneca vaccine and those involved in the Russian Sputnik V shot, due for UAE trials, both hope to get the vaccine approved for widespread use by late 2020.
The experimental US vaccine trialled by Johnson & Johnson is thought to be several months behind that.
“For the best results, we aim to give two doses of the vaccine, but it is impossible to know exactly when this vaccine will be rolled out,” said Prof Sarah Gilbert, a vaccinology expert in the Nuffield Department of Medicine at the University of Oxford.
“The two top targets for prioritisation will be heath workers and older populations who are more at risk.
“Getting the vaccine out will take some time, but we expect to get the efficacy results and aim for regulatory approval by the end of the year.”
Manufacturing by AstraZeneca is taking place at multiple sites around the world, with large scale plants in India capable of supplying vaccines to low and middle income nations.
Studies have been initiated by Oxford on people with HIV to learn how they respond to the jab so they could be added to the vaccine’s licence in future.
Reproductive toxicology studies are also under way before trials can begin on pregnant women.
Children have not been part of any vaccine trial yet. Most young people with Covid-19 show mild symptoms and recover quickly.
Two shots, 21 days apart
Trials at the University of Oxford started 104 days after the viral sequence was released by scientists in Wuhan, China.
Non-human primates were vaccinated with either one or two doses of the vaccine.
Vaccinated monkeys had a significantly better defence to Covid-19 than those who had not been inoculated.
Further east, Russian scientists said no serious side effects had been reported in the Sputnik V vaccine, due for human trials in the UAE.
Pre-registration clinical trials of the Sputnik V vaccine are expected to include human trials on 40,000 subjects.
But preliminary results will be only be ready in early 2021, they said, with efficacy results only made available on completion of the large scale clinical trial.
“There is sufficient data on safety that a vaccine can be circulated under special conditions,” said Dr Denis Logunov, deputy director for science at the Gamaleya centre.
“The vaccine has a provisional registration as it is being conducted in civil circulation where 10,000 teachers, medical workers, social workers and others have been vaccinated.
“This is in parallel with clinical trials with 20,000 volunteers with a single dose and 12,000 volunteers with both doses of our vaccine.”
The vaccine is being manufactured at four production sites with the aim of producing millions of doses by the end of the year to vaccinate the population of Russia.
To expand the technology abroad, Russian scientists are working with production facilities in Brazil, India, Korea and China.
In the second stage of trials, subjects were given two doses of the vaccine, 21 days apart.
When analysing safety, scientists could demonstrate averse side effects such as mild hypothermia, headaches, muscular and joint pain or pain at the injection site.
All were considered generic for the vaccine and expected.
Scientists said that, because the side effects were very minor, they could demonstrate a good deal of safety.
Prof Dan Berouch, an expert from Harvard Medical School and the US Centre for Virology and Vaccine Research, said clinical trials on the vaccine tested by the Beth Israel Deaconess Medical Centre and Johnson & Johnson were yet some time away.
“We are reluctant to give a calendar date for when clinical trials may end,” he said.
“There will need to be some time for regulatory approval and roll-out, but there are still a lot of uncertainties.
“For our programme we started Phase-3 trials after the other groups so we expect to be several months after other groups in the field.”
