Child wearing glasses showing arm after vaccine

How Covid-19 has changed the way we look at vaccines. (Spoiler: It’s not for the better.)

Aug 31, 2021 COVID-19 Share:

When the first Covid vaccines were introduced, it felt like a miracle. These vaccines were safe, effective, and available just a year after the world was first exposed to the novel coronavirus. So far, the Covid vaccines available in the United States have been very effective at preventing serious illness, hospitalization, and death from Covid-19.

Unfortunately, with the rise of the Delta variant, we’re seeing that the effectiveness of the vaccine was narrow, weak, and short-lived. But the current Covid vaccines are very different from any vaccines you’ve ever gotten before.

As breakthrough infections continue to rise, don’t lose your trust in vaccines altogether. Traditional vaccines are safe and effective. And to stay healthy, it’s important to stay up-to-date on your vaccines.

A brief history of vaccines

While the technology used to create the Covid vaccines is fairly new, vaccines themselves have been in use for over 200 years. Vaccines have been effective at eradicating deadly diseases such as smallpox and polio, and they are responsible for drastically extending life expectancy.

The first true vaccine was developed for smallpox in 1796 by a British physician named Edward Jenner. Smallpox was a contagious and deadly disease that killed around 30% of the people it infected. Those who did survive a smallpox infection were known to be immune.

Jenner noticed that milkmaids also appeared to be immune to smallpox. He believed that their immunity came from infection with a similar, but much less serious, illness called cowpox. Jenner theorized that inoculating people with cowpox would be a safe and effective way to prevent smallpox infection.

Jenner’s experiment worked. Over the next 50 years, smallpox vaccines became more commonplace and eventually became mandatory in the United States. The World Health Organization declared that smallpox had been eradicated in 1980, and no naturally occurring cases of smallpox have happened in the United States since 1949.1

The smallpox vaccine used a similar, weaker virus to prevent smallpox infection, but this technology couldn’t be applied to other diseases. In 1885, Louis Pasteur developed a vaccine for rabies that used an attenuated (or weakened) form of the rabies virus that had been grown in a lab. Almost all of the vaccines available today use either a live, attenuated virus or an inactivated (or killed) form of the virus to create an immune response.

How do traditional vaccines work?

Live attenuated vaccines are developed through repeated culturing of the virus in a lab. As the virus replicates over time, the virus weakens. When you’re injected with an attenuated virus vaccine, your body is able to fight off this virus and develop immunity. The virus you receive in the vaccine causes such a mild illness that most people won’t experience any symptoms.

Killed or inactivated vaccines are developed by removing the pathogenic element (the part that makes you sick) of a virus. This inactivated form of the virus is then replicated in a lab. When you receive an inactivated vaccine, your immune system is able to see the virus and know how to fight it if your body is exposed to it later.

Both live, attenuated vaccines and inactivated vaccines work by showing your body an illness and allowing your body to fight off a form of the illness that won’t make you sick. If you do encounter the wild form of the virus after you’ve been vaccinated, your immune system will know exactly how to fight it off and prevent illness.

How are the Covid vaccines different?

When the Covid vaccines became available, the data pointed to these being the best way to help us through the pandemic. The safety and efficacy data was incredibly promising for all three vaccines available in the United States. Remarkably, the first vaccines were distributed less than a year after Sars-CoV-2 was first identified in China.

Scientists were able to develop these vaccines so quickly because they’re based on a very different type of technology that’s been in development for about 20 years. The Pfizer and Moderna vaccines are both based on mRNA technology, while the Johnson & Johnson vaccine is a viral vector vaccine.

Your cells use mRNA all the time. mRNA (messenger RNA) provides instructions to your cells to create proteins that play many important roles in your body. The Pfizer and Moderna vaccines use mRNA to instruct your cells to make proteins that look like the spike protein on the coronavirus. When your body sees this foreign protein in your body, it triggers an immune response. Your body makes antibodies to the coronavirus and can protect you from the disease.

The Johnson & Johnson vaccine also uses spike protein messaging, but instead of using mRNA, it delivers the message to your cells using a weakened viral vector (or carrier). The viral vector won’t hurt you, but because it’s a virus, it’s effective at getting into your cells and delivering the spike protein messaging. While the mRNA vaccines deliver the message directly, the viral vector vaccine “wraps” the message in a viral package or envelope.

The Covid vaccines have so far been incredibly effective at preventing serious illness and death. But with the rise of the Delta variant, these vaccines are no longer very effective at preventing breakthrough infections. In fact, data indicates that vaccine effectiveness seems to drop after only a few months.2

So what happened with the vaccines?

The vaccines actually haven’t changed at all, but Covid has. All viruses mutate, and scientists were never surprised that Covid-19 also developed multiple variants. While the Covid vaccines were initially effective at preventing infection from the variants as well, the Delta variant was much more adept at bypassing the protection provided by the vaccines.

When you vaccinate against any infectious disease while it’s still circulating in a community, there’s a risk that escape variants (like Delta) will emerge. In other words, the circulating virus is going to evolve and change in such a way that it can break down the defenses provided by the vaccine, like a persistent intruder.3

In most cases, if you’ve had a Covid vaccine, Delta (and other Covid variants) may be able to bypass the neutralizing antibodies that keep you from getting sick at all. But cellular immunity will protect you from serious illness. Vaccinated individuals who contract Delta may experience some symptoms of coronavirus, but they are usually mild and short-lived.

If you’ve already had a previous Covid infection, research indicates that you have more robust and durable protection against the variants.4 However, if you’ve not been exposed to the coronavirus through prior infection or vaccination, the Delta variant is still a novel virus that your immune system doesn’t know how to fight.

How you should think about vaccines

While the Covid vaccines have helped mitigate severe illness, the vaccines based on spike protein messaging have simply not been as effective as scientists hoped. Escape variants have developed that can bypass the vaccine’s protection. It also now appears that protein messaging for another protein on the coronavirus may have been more effective. Unfortunately, vaccines haven’t been a “magic bullet” for ending the pandemic.

Medicine is imperfect, and scientists work with trial and error. In fact, there are currently over 100 Coronavirus vaccines currently in various stages of development and testing utilizing several different technologies, including traditional attenuated and inactivated vaccines.

But while Coronavirus vaccines are still being tested, remember that these are not the same as the vaccines we’ve had historically. The traditional vaccines that have been administered for years on the pediatric vaccine schedule, as well as those that are given in adulthood, are incredibly safe and effective. These vaccines have been thoroughly tested and proven to be effective through years of use.

Even amid another wave of Covid-19 infections, it’s important to make sure that you stay up-to-date on any needed vaccines. Children should also continue to receive all of their vaccines according to the recommended vaccine schedule. You should also be sure to get your flu shot this year. Flu shots will be available soon and can not only protect against the flu but can also provide other benefits in the context of Covid-19.

The news about Covid vaccines can be confusing. You should always talk with your primary care doctor before deciding to get any vaccine. Your doctor can help you know which vaccines you need and when.

Vaccines available at MedHelp

Whether you need vaccines for school or work or you’re just looking to get your flu shot, MedHelp can help you get up-to-date. Walk-ins are welcome for vaccine appointments.


1 CDC: Smallpox. Retrieved August 20, 2021.

2 Favresse, J., et al. Antibody titers decline 3-month post-vaccination with BNT162b2. Emerging Microbes & Infections. July 07, 2021.

3 Rella et al. Rates of SARS-CoV-2 transmission and vaccination impact the fate of vaccine-resistant strains. Scientific Reports. July 30, 2021.

4 Cohen et al. Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells. Cell Reports Medicine 2, 100354 July 20, 2021.