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Why it takes time to produce a Covid-19 vaccine

By DR. EDUARDO GONZALES

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Despite the radical approaches—mass quarantine, lockdowns, and social distancing rules—that most governments worldwide have adopted in stemming the Covid-19 pandemic, don’t expect the disease to go away anytime soon. But what these extremely costly measures will do, with hope, is slow down the spread of the disease to levels that our health care delivery systems can cope with and buy time for vaccine developers all over the world to prepare and test their vaccines. Arguably, the key to eradicating Covid-19 is a safe and effective vaccine.

Some good news on the Covid-19 vaccine

One good news coming out of some laboratories is that the SARS-Cov-2 virus has been relatively stable during its global spread—it does not mutate at a high rate. This means the vaccine that will ultimately be developed for the virus would be a single vaccine similar to the vaccines for the measles and chickenpox, which offer long-lasting immunity, unlike the flu virus that mutates so fast that a new vaccine has to be developed every year.

Another good news is that pharmaceutical companies and research labs around the world are working at a breathtaking pace to develop a Covid-19 vaccine. They are making good progress, too.

But despite all this good news, don’t expect a Covid-19 vaccine to be available for mass immunization anytime soon. It takes time to produce a new vaccine because vaccine development is a complex multi-stage process. It starts with a research intensive phase of identifying the antigens (parts or weakened strains of a virus) that will be incorporated in the vaccine. Then, tissue-culture or cell-culture and animal testing are performed to find out if the candidate vaccine will produce immunity.

This is followed by clinical testing, which encompasses three stages. Phase one entails testing for safety and immunogenicity in normal adults (less than 100 people); phase two entails testing for immunogenicity and safety in special populations (hundreds of human subjects)—this phase aims to deliver more information about safety, immunogenicity, immunization schedule, and dose size. Phase three, which can include thousands or tens of thousands of test subjects, continues to measure the safety (rare side effects sometimes don’t appear in smaller groups) and effectiveness of the candidate vaccine. After the clinical trials, the candidate vaccine is submitted for regulatory review and approval. If approved by regulatory authorities (e.g., FDA), the vaccine is manufactured.

At the moment, many drug companies have the capacity to produce millions of doses of vaccine per year. It should therefore take a very short time to produce all the vaccines the world needs if and when a Covid-19 vaccine is approved.

When should we expect the Covid-19 vaccine to be ready for manufacturing?

Some of the candidate vaccines have already started clinical trials. If the clinical trial phases go well, a Covid-19 vaccine could be ready for public use in about 12 to 18 months. That’s still a long time. But you see, despite the urgency, you can hurry up vaccine development by only so much.



Source: Manila Bulletin ( https://lifestyle.mb.com.ph/2020/04/16/why-it-takes-time-to-produce-a-covid-19-vaccine/)

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