A Deep Dive on Vaccines

Illustration by Sahana Maheswaran

Coming up with a vaccine is not an easy process. When tests first detect a new virus, scientists must determine if the virus is viral or bacterial, what the symptoms are and how it spreads.

History of Vaccines

Vaccines go back a very long time. From immunizing people against specific pathogens to prevent infection, to limiting a virus's impact once infected. The word vaccine comes from the word vaccinia, which was discovered because of the cow pox virus, which was used to immunize against smallpox.

David Topham, a professor of Microbiology and Immunology at the University of Rochester, shared insight on their origins.

“It’s a cow virus, it caused minimum disease in people but it was similar enough to human smallpox that it provided immunity,” Topham explained.

The cow pox virus was the first vaccine developed by humans. However, it wasn't until the early 1900s, during the Spanish flu pandemic in 1918, that scientists really knew what had caused the virus in the first place.

It took almost 12 more years before scientists identified the H1N1 influenza A virus. When it comes to bacterial viruses, we have a lot of resources like antibiotics to stop the spread. With viral viruses it can be more difficult — or in cases of human immunodeficiency virus (HIV) where there is no vaccine or cure.

“HIV is a virus that mutates very rapidly even within a person. A lot of other viruses — they mutate between people but not within a person,” Topham stated.

HIV can also lie dormant in a person by integrating into their DNA and becoming invisible to their immune system, thus going undetected for a long time.

When it comes to HIV, all modern medicine can do now is suppress how much the virus replicates in humans.

“It's been hard to come up with a vaccine that works because there's literally hundreds of thousands, if not millions, of variants of HIV in the world, and even within a person there are thousands of variants,” Topham explained.

Before COVID-19, there was the Ebola outbreak, one that took years to try and control.

“I know there's still ongoing efforts to create safer and safer vaccines for Ebola and other pathogens. ... We needed to move very quickly to get a vaccine to protect people,” Topham said.

Even with a long history of vaccines and viruses, Topham pointed out that misinformation about vaccines still exists. If people don’t take vaccines because of misinformation, there can be long-term consequences as viruses continue to spread.

“The false link to autism was probably one of the most damaging things to have affected the use of vaccines. It was a completely fabricated study and has been discredited many times,” Topham stated.

Different Types of Vaccines

There are a lot of different ways that vaccines can be approached, and that also has to do with what type of virus is being dealt with. Technology has been a huge influence in how far we’ve come when producing vaccines.

One of the early strategies used was inactivating the virus and putting it back into the person. Inactivating a virus is the act of either removing the virus completely or rendering it non-infectious.

Furthermore, the attenuated vaccine is another approach to developing vaccines and is often a time consuming, expensive and labor-intensive procedure. This type of vaccine is normally thought of in regards to the flu and is looked at yearly. The attenuated vaccine does takes the infectious agent and alters it to make it less harmful.

Maureen Ferran, associate professor in the Gosnell School of Life Sciences, explained that process.

“You take a human virus and you put it in an egg ... Get out the little bit of virus and put it in another egg and it infects a little bit better," Ferran explained "You transfer it from egg to egg until it gets better infecting an egg than a human and we call it attenuation.”

One kind of technology that has been discussed a lot lately when it comes to vaccines is messenger RNA (mRNA). The practice of editing mRNA to make new proteins has been around for the last 20 years.

“It’s been an idea that people have been fine tuning and honing ... then all of a sudden when you have this global pandemic and everyone has this need to do something they turn to all these other ideas [mRNA],” Ferran stated.

Efficacy and Time

When people think of vaccines, one of the first questions include how effective the vaccine will be and how many doses they will need, especially when it comes to COVID-19.

"Immunizing too close together becomes less effective ... if you wait long enough you get a much stronger response."

Efficacy depends on what’s being measured, whether it’s death, hospitalizations, moderate disease or mild disease.

The Moderna and Pfizer vaccines for COVID-19, for example, look at mild or moderate disease (fever, cough and shortness of breath) and get close to the 90 percent area for efficiency.

“Until very recently we had very few vaccines that approached anywhere close to 100 percent, like the yearly flu vaccine’s can be in the 50s, low mid 60 percent in terms of efficacy,” Ferran explained.

It is important to understand that vaccines like those of Moderna and Pfizer are closer to 100 percent effective when looking at hospitalizations and death.

With COVID-19 vaccines, the CDC recommends getting the second dose around 21 or 28 days apart from the first dose. But why is that time frame important? What happens when you’re a little off?

The reality of it is that there is no scientific backing to time frames when it comes to primary and secondary doses. Sometimes it might be better to wait three or six months to get a booster shot.

"We know that immunizing too close together [the vaccine] becomes less effective. We also know that if you wait long enough you get a much stronger response then you get at, say, 28 days,” Topham said.

Nonetheless, the reason why people shouldn’t wait that long with COVID-19 vaccines is because there are still very high infection rates. People need to be vaccinated quickly in order to stop the spread.

The Future

“I think we’re seeing a paradigm shift in vaccinology. I think it will never look the same,” Ferran stated.

“I think we’re seeing a paradigm shift in vaccinology. I think it will never look the same.”

Technology has allowed us to improve vaccines throughout the years and because of this we are able to make some vaccines quicker and make them safer. Only time will tell what comes next for vaccines.