COVID-19 vaccine updates: Understanding Pfizer results, Moderna up next

All you need to know about the latest vaccine developments


After US biotech company Pfizer and Germany's BioNTech SE announced that their vaccine candidate was found to be more than 90 per cent effective in preventing COVID-19, a slew of similar data from its competitors is expected soon. Moderna Inc said it has enough data for a first interim analysis of the late-stage trial of its experimental COVID-19 vaccine, which should help determine the vaccine's efficacy. Moderna said the information is being prepared for submission to the trial's independent data safety monitoring board, which will look at the results and make a recommendation. It did not say when it plans to release the data. 

On the back of Pfizer results, Russia announced that its Sputnik V vaccine has shown 92 per cent efficacy in preventing COVID-19, according to interim trial results announced by the country's health ministry. The efficacy of the vaccine, developed by the Gamalaya Centre, was demonstrated on the basis of a first interim analysis obtained 21 days after the first injection. There were no unexpected adverse events during the trials. Monitoring of the participants is ongoing, the ministry said. Currently, 40,000 volunteers are taking part in Phase III of Sputnik V clinical trials, out of which over 20,000 have been vaccinated with the first dose of the vaccine and more than 16,000 with both the first and second doses of the vaccine.

The shots made by Pfizer are among 10 possible vaccine candidates in late-stage testing around the world.

How are the results calculated?

Every vaccine study is overseen by an independent data and safety monitoring board, or DSMB. These boards include scientists and statisticians who have no ties to the vaccine makers. The trials are double-blinded, that is neither the company nor study investigators know which participants received the vaccine or a placebo. Before a study is complete, only the DSMB has the power to know who got the real vaccine and who got placebo, and to recommend if the shots are working well enough to stop testing early. Those boards take sneak peeks at pre-determined times.

The vaccine will be deemed a success if the overwhelming majority of those infected had received a placebo (and not the vaccine shot), once the monitoring board looks at the early results. 

The first interim analysis for Pfizer came on Sunday. The company reported its data monitors had counted 94 infections so far, and that among those initial cases, the vaccine appeared 90 per cent effective. But the study isn't stopping: To be sure of protection, it is set to run until there are 164 infections. The more COVID-19 cases occur in the trial, the better idea scientists will have of just how protective the shots really are.

It need not reach the infection tally of 164 though, as companies are expected to seek permission for emergency use of their vaccines, rather than waiting to fully complete their studies and then seeking traditional approval.

What are India's plans?

The Union health ministry on Tuesday said the National Expert Group on Vaccine Administration for COVID-19 is in conversation with all vaccine manufacturers, including domestic and foreign ones.

Asked if India is considering a tie-up with Pfizer for its COVID-19 vaccine and whether it has the infrastructure for specialised cold chain requirement for this vaccine, Union Health Secretary Rajesh Bhushan said, "The National Expert Group on Vaccine Administration for COVID-19 is in talks with all vaccine manufacturers, including domestic and foreign manufacturers." 

Most vaccines in India need to be stored at a temperature of two to eight degrees Celsius. The lowest minimum temperature at which vaccines can be kept to maintain the cold chain in most areas in the country is minus 25 degrees Celsius. The extreme low temperature of minus 70 degrees Celsius required for storing a potential COVID-19 vaccine developed by Pfizer poses a big challenge.

"When we continue this dialogue, we not only look at the status of the development of their vaccines, we also look at the regulatory approvals as to where they have progressed and we also engage in a dialogue about the logistical requirements, if such vaccines have to stored at temperatures that may range from two to eight degrees to minus 50 to minus 90 degrees Celsius as well as the doses that will be required to be administered," Bhushan said.

Asked whether the vaccine would only be available in the metro cities initially since the Centre is planning an early 2021 roll-out, Bhushan said the government does not make any discrimination between metro cities and non-metro cities. "Whenever the regulatory approvals for the vaccines are provided, we have a plan that would ensure that the vaccines would be available to all priority population groups, irrespective of the region where they reside," he clarified.

Responding to another query on vaccine administration, he said, "We are in a position to not only augment and strengthen, but also to add to our cold chain capabilities." Any large-scale immunisation would not only require a substantial increase in the number of cold-chain points, but also a huge rise in the number of cold chain equipment, Bhushan added.

-Inputs from agencies