Duration Of COVID-19 Vaccine-Induced Protection Unknown Due To Shortened Trials - MSF

MOSCOW (UrduPoint News / Sputnik - 27th November, 2020) Shortened trials for coronavirus vaccines worldwide make it difficult to predict the duration of protection they provide, as well as long-term side effects they might have, the senior vaccines policy advisor for Doctors Without Borders' (MSF) Access Campaign told Sputnik.

"On safety, while all most vaccines will have gone through all the regular phases of approval, the shortened timeline does mean that we will not have enough clinical data to determine the length of protection granted by an approved vaccine and will be largely unaware of long-term safety concerns as well as very rare ones (e.g. 1:100 000)," Kate Elder said.

Vaccine developers therefore should keep monitoring those who have received jabs to learn the possible longer-term effects, according to the MSF official.

"Given the short clinical development timeframe, special attention needs to be paid to safety and post deployment monitoring of adverse effects. The manufacturer needs to come up with a clear safety monitoring plan and make sure it is followed in countries of use. Safety signals need to be duly collected, analyzed and transmitted to the regulator," Elder argued.

The expert also pointed to a lack of comparative clinical data on vaccines, even at the stage when some of them expect regulatory approval.

"The scale of individual clinical trials in many cases seems adequate but as we expect several vaccines to reach licensure, the lack of comparative clinical data is a problem. Biomarkers measured during phase 1 and 2 studies have been evaluated using different parameters and assays, making cross-candidate comparisons difficult. The same also goes for phase 3 trials, where the Primary and secondary outcome measures differ from candidate to candidate, making comparisons between vaccine candidates tricky. There is also a missed opportunity to conduct a solidarity trial (as was done for therapeutics) for vaccines," she added.

At present, there are 48 candidate vaccines on the World Health Organization's list. Some manufacturers have already begun releasing the interim results of phase three trials of their candidate vaccines. Russia's Sputnik V, as well as candidate vaccines produced by Pfizer/BioNTech and Moderna, have all reported over 90 percent efficacy, according to the preliminary data. The average efficacy of the Oxford-AstraZeneca vaccine totals 70 percent, interim analysis shows.