What we know about how the COVID-19 vaccine was developed

A long-awaited vaccine for COVID-19 will soon be distributed across the globe, potentially bringing an end to the coronavirus pandemic. But the introduction of a COVID vaccine has many asking questions about its history, process and efficacy.

How is a vaccine made in the lab?

Viruses cause disease by reproducing themselves, often thousands of times, in the body. Vaccines are made by weakening a virus to prevent it from replicating, while still training the immune system to block the virus against infection.

Scientists can weaken the virus in four ways:

• Changing the virus’ blueprint or genes so it replicates poorly. This is how the measles, mumps, rubella and varicella vaccines were made.
• Destroying the virus' blueprint or genes, preventing it from replicating at all. This is how the polio vaccine was made.
• Using a fraction of the virus, preventing it from replicating itself. This is how the hepatitis B vaccine was developed.
• Taking the toxin released from bacteria, purifying it, and killing it with chemicals so it cannot do any harm. This is how the diphtheria, tetanus and whooping cough vaccines were developed.

How was the COVID-19 vaccine made?

Traditional methods for making a vaccine, while effective, are time consuming. Many of the leading vaccine candidates were developed by introducing targeted genetic material from the virus to create a coronavirus "spike protein" that will trigger an immune response with the recipient. Unlike previous vaccines, bits of the virus do not have to be generated in a lab. Instead, the vaccine delivers a genetic code that instructs cells to build certain proteins themselves.

How many coronavirus vaccines will soon be available?

Researchers are testing nearly 60 vaccines in clinical trials on humans. Among the most promising early candidates are vaccines from Pfizer and Moderna, which claim to be 95% effective against the virus and are expected to be available to a limited number of people in the United States later this month. Long Island will receive 26,500 doses of the Pfizer vaccine as soon as this weekend, Gov. Andrew M. Cuomo said Wednesday. Another vaccine by Oxford University and the biotech firm AstraZeneca could be on the way soon but has not proved as effective as others. A vaccine by the pharmaceutical company Novavax is in Phase 3 clinical trials.

What do scientists look for to help them decide it’s a success?

Clinical development of a vaccine is a three-phase process. During the first phase, a small group of people receive the trial vaccine. In the second phase, the clinical study is expanded and the vaccine is given to more people with similar ages and physical health for whom the vaccine is intended. In the third phase, the vaccine is given to thousands of people and tested for efficacy — to determine if it prevents the virus — and safety to see if there any side effects.

How does the race for a COVID-19 vaccine compare to previous efforts during past pandemics? Were they made under the same pressures and time constraints?

The race for a solution to the novel coronavirus is unique because of COVID's deadly nature and its ability to rapidly spread across the globe. The influenza pandemic of 1918, dubbed the Spanish flu, killed tens of millions across the globe, but it was not until the mid-1940s that a vaccine was distributed to the general population.

Virus expert Jonas Salk began work in 1953 on a vaccine for polio, which was paralyzing up to 20,000 children annually, and it was declared safe and effective two years later. But Salk’s method of inactivating the virus was used incorrectly by manufacturers, leading 200,000 children to receive vaccines containing the live poliovirus. Roughly 200 children were paralyzed and 10 died from the flawed vaccine.

Sign up to get COVID-19 text alerts.

By Robert Brodsky

robert.brodsky@newsday.com@BrodskyRobert

Robert Brodsky is a breaking news reporter who has worked at Newsday since 2011. He is a Queens College and American University alum.