Three Vaccines Use Other Viruses to Protect Against COVID-19

More than 5 million people worldwide have had their lives cut short by COVID-19, and the number keeps rising as many countries experience another wave of transmission.

The best defense against this disease is a vaccine, experts say.

Since the outbreak was first reported in 2019, the best scientists all over the world have been working on a vaccine to protect against SARS CoV 2, the virus that causes COVID-19. The acronym stands for “severe acute respiratory syndrome coronavirus 2” to distinguish it from the first SARS outbreak in 2003.

Historically, when scientists make vaccines, they have used a live virus that is so weak it can't reproduce, or they use a dead virus. When these weakened or inactive viruses are injected into the body, the body recognizes them as intruders, produces antibodies and fights them off.

Polio vaccines have used both weakened live viruses as well as dead ones with enormous success. The Global Polio Eradication Initiative reports that polio cases were reduced by 99.9% between 1988, when the global effort to eliminate polio was started, and 2021. The U.S. Centers for Disease Control and Prevention reports that without the global polio vaccination program, more than 18 million people who are currently healthy would have been paralyzed by the virus.

As of December 6, three children in the entire world have contracted the wild polio virus in 2021.

Three of the vaccines developed against COVID-19 are vector vaccines. A vector is simply a delivery system. In this case, scientists use an adenovirus -- a cold virus, for example -- to deliver a fragment of the coronavirus. The fragment is a gene from a spike on the crown of the coronavirus. This trains the body to fight off any other similar infections, including COVID-19.

The spike cannot infect someone with the coronavirus.

The Oxford-AstraZeneca vaccine uses a chimpanzee virus, not a human one. The Johnson & Johnson and Sputnik V vaccines use human adenoviruses. J&J uses a rare adenovirus. Sputnik V uses the same virus in its first dose. In its second dose, Sputnik V uses a common adenovirus that some people might be immune to. For this reason, many scientists are concerned that Sputnik V may not be an effective vaccine.

Once injected, the viruses enter the cells and start to produce the spike protein, but not COVID-19. Then, the body mounts an attack.

Dr. Andrea Cox, a professor with a specialty in immunology at the Johns Hopkins University School of Medicine, says our bodies don't just mount an immune response to the adenovirus, but they also produce an immune response to the spike protein from the coronavirus. In this way, the body learns to fight off the coronavirus if it sees it again.

The World Health Organization has authorized use of the AstraZeneca and Johnson & Johnson vaccines but not Sputnik V. The WHO says it needs more data from the Sputnik V trials.

Cox says the AstraZeneca and Johnson & Johnson vaccines are preferred because they have been given to hundreds of millions of people worldwide. Scientists have more information about their side effects and their immune responses than Sputnik V’s simply because Sputnik has been used far less frequently and there are fewer international studies that have assessed it.

Another issue with Sputnik V, Cox says, is "that the data are not showing the kinds of efficacy rates that we would like to see in a vaccine."

Some scientists expect COVID-19 to be with us for three to four years. But even with the best scientists in the world working on vaccines, they are concerned that as the virus continues to infect unvaccinated people and mutate, at some point, the vaccines we have now won't be able to offer full protection against COVID-19.

Source: Voice of America