Decoded: What emergency use authorisation of Covid vaccine means for us

After the Indian arm of US pharmaceutical giant Pfizer, the Serum Institute of India has applied to the Drugs Controller General of India (DCGI) seeking emergency use authorisation (EUA) for the Oxford Covid-19 vaccine in the country. Here’s what it means.  

What is EUA and when is it given?
 

EUA is when an unapproved medical product or unapproved use of an approved medical product is given marketing authorisation by a regulator in an emergency to diagnose, treat or prevent serious or life-threatening diseases or conditions.

This is unlike full authorisation, for which the regulator assesses more elaborate data collected over a longer duration of time.

Have EUAs been given during the Covid-19 pandemic?
 

Yes, drugs like remdesivir and favipiravir have been granted EUA. Remdesivir was developed for Ebola. Its innovator Gilead later submitted data collected from the drug’s use on Covid-19 patients and it got a full authorisation in the US. In India, however, the regulator has not yet granted remdesivir full marketing authorisation.

What does EUA change for people or patients?
 

The Indian regulator gave “restricted emergency use” authorisation for drugs like remdesivir. This means the doctor who prescribes the drug has to explain the risks and benefits to the patient and also clearly state that this drug does not have a full authorisation. The patient has to sign a consent form indicating that s/he has understood the implications.

Has any vaccine ever got an EUA?
 

No, there is no such precedence. Research to develop a vaccine takes several years and the data is collected and analysed over these long periods of time. The UK regulator granting Pfizer-BioNTech vaccine an EUA last week is the first such instance.

The USFDA grants an EUA when it satisfactorily determines that the known and potential benefits of the investigational product outweigh the known and potential risks. EUA is never granted based on only phase 1 and 2 clinical trial data (which are necessary to ascertain that the product is safe). EUA is considered only after sufficient efficacy data is generated in a phase 3 trial. For Covid-19 vaccines, the USFDA has specified that it would consider an application for EUA only if the phase 3 data showed it was at least 50 per cent effective in preventing the disease. This data needs to be generated from over 3,000 trial participants who have been followed up for any serious adverse events for at least one month after all doses have been given.

India has also indicated that it would consider a vaccine candidate that has shown to be at least 50 per cent effective in preventing the disease.

Why are vaccines being given EUA and not a full authorisation?
 

The research to develop a safe and effective Covid-19 vaccine has been accelerated in 2020. This has never happened before. Accelerated reviews of clinical trial data does not mean the trials have been rushed. The trials on subjects have taken their usual time, with the doses been given at stipulated intervals. The recruitment of subjects has been a faster process and the regulator has been reviewing the data from these trials from time to time. This interim reviewing of data did not happen earlier. The regulator would review the data once the trial was completed and the sponsor analysed and presented the data.
 

Now, the second important aspect here is that in this case, time is of the essence. The regulator would need long-term immunogenicity data (whether the vaccine induces the desired immunity against a disease pathogen) from the trials. One may produce antibodies against the pathogen now, but it is important to see if the person also develops what we call memory-cell immunity. This means that if exposed to the pathogen after a long period of time (say, one year) s/he still produces antibodies.

At the moment, no vaccine maker would be able to submit this long-term data. For example, Serum Institute of India, which was conducting phase 3 safety and immunogenicity trial on 1,600 Indian subjects for the AstraZeneca-Oxford vaccine, has finished the trials in November. It has applied for EUA in the first week of December. There is no way it can provide long-term data now.
 

Regulators would thus review this interim data from the trials and decide if it merits an approval for use during the pandemic. Long-term data would be subsequently submitted to the regulator from time to time to get a full authorisation.

What next after a firm applies for EUA?
 

The Drugs and Cosmetics Act and Rules, 1940 and its amendments do not mention anything about EUA. Industry insiders explain that India is primarily a generic drugs market and there has been no major need to approve an investigational drug or medical product for emergency use based on interim data. The regulator has given restricted emergency use authorisation to drugs like remdesivir and favipiravir for treatment in Covid-19. The clause 26B of the Act states that the Central Government can regulate or restrict, manufacture etcetera of a drug in public interest if it is essential to meet the requirements arising due to epidemic or natural calamities. If in public interest, it is necessary or expedient to do so, then the government may by an official gazette notification regulate or restrict the manufacture, sale or distribution of such drug.

For the vaccine, it would take the help of a subject expert committee (SEC), which will analyse the scientific data made available – and especially consider it from the perspective of the Indian demographic to arrive at a decision. The DCGI would act under advice from the SEC in this case.
 

While sources indicate that a decision is likely within 90 days of the EUA application being submitted, there is no clear guideline on this. As for clinical trial applications, the Drugs and Clinical Trials Rules, 2019 say that if the regulator does not respond to an application to conduct clinical trials in India within 90 days for a globally developed product and within 30 days of an indigenously developed product, then it is deemed as a go-ahead. However, in case of EUA, one does not clearly know if there is such a timeline.

Will I be able to get a vaccine shot that is approved under EUA?
 

Yes. The vaccine would be first made available to the vulnerable population and eventually, it would be available in the private market for all. Since we are in the middle of a pandemic, the government and policy makers would have a say in the way the vaccine is distributed so as to ensure effective mitigation of the risks to larger populations.