Why GSK (LON: GSK) and Sanofi's (EPA: SAN) Covid-19 vaccine got delayed to 2021-end?

Summary

  • The Covid-19 vaccine jointly developed by Britain’s GSK and France’s Sanofi has been delayed to the end of 2021
  • Both the pharmaceutical companies are expected to start Phase 2b studies in February 2021

While the companies are hurrying to get Emergency Use Authorization (EUA) from top regulatory bodies, French drugmaker Sanofi SA (EPA: SAN) and Britain's GlaxoSmithKline (LON: GSK) have said that their Covid-19 vaccine will be delayed by almost a year and won't be ready for distribution till the end of 2021.

The companies were forced to declare the delay as the trials have shown that the vaccines have failed to develop a strong immune response in older people.

Reason for the delay

The interim results of Phase 1 and 2 clinical trials of the GSK-Sanofi vaccine have indicated a better immune response in the adults between the age group of 18 and 49 years as compared to the older patients who recovered from coronavirus.

Both the drugmakers are now ideating to incorporate an improved antigen formulation in the Phase 2b study. In order to provide a high-level immune response across all the age groups, there is a certain requirement of rectification in the concentration of the antigen as it has proved effective for older patients.

In the interim results of the Phase 1/2 clinical trials, a level of neutralising antibody was seen after injecting two doses. As per GSK, no serious adverse effects were seen; however, the volunteers showed “higher-than-expected levels of reactogenicity”.

The reactogenicity was short-lived and possibly occurred due to the “suboptimal antigen formulation,” the drugmaker confirmed.

A vaccine with an improved antigen concentration has demonstrated that the viral traces can be cleared from nasal passages and lungs within two to four days, GSK said, adding, such results boost the belief of the firms to deliver a highly effective vaccine for all adults.

Also Read: Pfizer’s COVID-19 vaccine receives a go-ahead sign from FDA Expert Panel

Phase 2b study

The Biomedical Advanced Research and Development Authority, which is part of the US Department of Health and Human Service office, will be supporting the Phase 2b of the GSK-Sanofi Covid-19 vaccine. The potential availability of the GSK-Sanofi coronavirus vaccine can now be expected between mid-2021 and Q4 2021.

The vaccine makers have also decided for a proposed comparison of their vaccine shot with another clinically authorised vaccine in the Phase 2b study that is expected to start in February 2021.

According to GSK, the global Phase 3 trials of the GSK-Sanofi vaccine could begin in the second quarter of 2021 if the outcome of the Phase 2b study is positive. The companies expect to file for a regulator’s authorisation of the vaccine in the second half of 2021 if they get promising results in Phase 3 clinical study.

With the unplanned delay in the vaccine development program of GSK and Sanofi, their vaccine is now expected to be available in the fourth quarter of 2021. 

Shares reaction

Following the announcement of vaccine deferment, the shares of GSK Plc were largely unchanged. While the Euronext-listed stock of Sanofi tumbled over 3 per cent in the morning deals.

As per the data available with the London Stock Exchange, the stock of GSK Plc was trading at GBX 1,420.40, up 0.21 per cent at around 14:33 (GMT), after swinging between a high and low of GBX 1,428.90 and GBX 1,407.40 on 11 December.

GSK Plc (11 December)

(Source: Refinitiv, Thomson Reuters)

The stock of Sanofi slipped as much as 3.31 per cent to hit a day’s bottom of EUR 79.08 from the previous closing price of EUR 81.79. As the trading progressed, the stock recovered partially and was trading at EUR 79.90, down 2.31 per cent at around 15:21 (GMT+1) on the Euronext Paris.

Sanofi SA (11 December)

(Source: Refinitiv, Thomson Reuters)

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