How is the COVID-19 vaccine's safety and efficacy ensured? I volunteered for a trial of the Oxford-AstraZeneca vaccine and saw firsthand how scientists and doctors make sure that it is safe and effective before releasing it to everyone.

The Oxford University-developed vaccine made by Serum Institute of India under the brand name Covishield began to be distributed in India last month as a part of what could be the world's biggest vaccination programme, and in dozens of countries on four continents.

It was already the mainstay of Britain's anti-coronavirus drive.

I joined the trial conducted by the New York University Langone Vaccine Centre in New York City, and received two trial injections.

It is a Phase III trial with about 30,000 volunteers that followed two limited trials and is similar to the exacting trials conducted in India, Britain, Brazil and elsewhere.

Mark J. Mulligan, the director of the vaccine centre, said the approval for it based on the trials can be trusted because an independent of body experts who are not connected with the company will review the data and decide if it can be used.

Although the vaccine development and the trials have proceeded very quickly, the safety will not be compromised, he said.

“Usually, this process would take years but because there's so much infection right now we can get the answer quickly. So that's why we can move to the emergency use authorisation,” he said.

The study I am in is a double-blind trial, with two out of every three volunteers receiving the actual vaccine and the other a placebo – a dummy injection of harmless saltwater -- without knowing which they received. I won't know if I got the real one until the study is over, probably next month.

Mulligan explained the need for the double-blind study where some volunteers get the placebo.

“We use the blinded controlled design, so that we can actually answer the question, 'Does the vaccine protect, (those getting the vaccine) compared to a control group (that doesn't)'?” he said. “It's really the only way we can ever discover if new medical interventions are truly effective and, of course, say we're looking at safety all the time.”

The reason to not let the participants if they were getting the real one or the placebo is that if someone knew they received the vaccine they might behave differently where it comes to wearing the mask or exposure to large crowds, he said.

After I received the first injection, the only reactions I had were a slight temperature, a sore arm where I got the shot, tiredness and a very mild rash on my shoulder. They disappeared in a day.

But it doesn't necessarily mean I got the real vaccine because it could be a psychosomatic reaction – a subconscious response even if I didn't get it based on what I had read should be the side-effects.

After the second shot, I had a similar reaction, except for the rashes.

Mulligan said, “I like to tell my study volunteers and my patients that it's a good thing when you're having these vaccine reactions. It means you're mounting a strong response to the vaccine and it's not a safety concern at all.”

The study collects data in three ways to establish its safety and efficacy.

A doctor and a nurse in the programme interview me periodically to check for reactions.

They also collect my blood at intervals so it can be tested to see if the vaccine has been effective in producing the antibodies. In fact, the programme has scheduled blood draws for me over a two-year period to find out how long the vaccine is effective.

Every week I also have to fill out an electronic diary about my health status and if I have any COVID-19 symptoms, which I haven't had. (Even a COVID-19 test that I took independently outside the vaccine trial programme as a condition to attend an event was negative.)

Before I was given the first dose, the vaccine trial staff took down my medical history and a doctor gave a physical exam so they would have a standard to compare any changes later on.

“We always regard our clinical trial volunteers as heroes as you know you're acting for the good of humanity to help us defeat the pandemic,” Mulligan said.

While I wanted to contribute to the vaccine's development, I did not think there was a personal risk for me in the trial because the participants in the first two phases had established that there was no safety risk. It's them that I consider the real heroes, especially those in the first trial; they took the real risks, not me.

Mulligan said that before the human trials start, a lot of initial work is done in the laboratory and with small animals. Once it is established that the vaccine is likely to be safe and effective, the manufacturers ask the Food and Drug Administration in the US for permission to conduct human trials. In India, the Central Drugs Standard Control Organization (CDSCO) authorises the trials.

The Phase I trial usually has 50 to 100 people “and is really designed to expose a small number of individuals to the vaccine to be sure it's safe,” Mulligan said. It is “focused on safety but starts to look at the immune response and if everything looks good in phase one you proceed to Phase II,” he said.

In Phase II may be between 200 to 500 people are enrolled and if it confirms the safety and immune response seen in Phase I, the trials move to the next phase where thousands are enrolled. With a pretty strong evidence base for safety, “in Phase III you're asking a very important question, 'Does the vaccine protect'?” he said.

The participants in the trial were selected to reflect the diversity of the population, including race, ethnicity and age. They also had to have some exposure to the disease rather than being in isolation, and in my case it was covering meetings and protests.

Mulligan pointed out that it is important to know that the emergency use authorisations for vaccines are not the same as full approval or licensure.

“They're saying that based on the totality of the available evidence we believe that the safety and the benefit are such that it's reasonable to use these vaccines in the public health emergency,” he said.

The companies will still be required to apply for full licensure down the road and they will continue to collect safety immune response protection data and report them to the regulatory authority, he said.

The Oxford-AstraZeneca vaccine, which has received emergency use authorisation from the World Health Organisation and dozens of countries, has the potential to be a game-changer in the global fight against the COVID-19 pandemic.

“It is a very important vaccine,” Mulligan said because of “the easier storage (at 4 degrees) but also because it can be produced in large numbers. AstraZeneca said it can make up to 3 billion doses this year.”

In India alone, the Serum Institute of India has a target of 1.5 billion doses this year and expects the capacity to increase to 2.5 billion per year by the end of the year.

Besides supplying Covishield to the Indian government for domestic vaccinations and donations to other countries, Serum Institute, according to the WHO, is expected to supply 240 million doses in the first half of this year to COVAX, the global vaccination drive for developing countries.

The first shipment under the COVAX programme was delivered to Ghana on Wednesday.

(The writer is Senior Nonresident Fellow, Society for Policy Studies (SPS), New Delhi. He can be followed on Twitter at @arulouis)