Viruses and bacteria have similarities, but the ways we defend against them are different

Adam’s Journal

Here’s a question from a reader: What’s the difference between viruses and bacteria?

Dr. James Prescribes

Bacteria and viruses are often lumped together as germs, and they share many characteristics. They’re invisible to the human eye. They’re everywhere. And both can make us sick, even kill us.

That last part is key. Because to fight them, we need to know which is which, as we use different approaches to stop them.

A virus is simpler. It’s just genetic material wrapped in proteins. Researchers debate whether viruses are even a living organism, as they can’t reproduce on their own. However, as we were often reminded during the COVID-19 pandemic, they can survive in the air or on surfaces for a period of time.

Viruses need to enter a living body to reproduce. When they do, they hijack that body’s cellular machinery and cause it to make more copies of the virus. When the virus replicates faster than the immune system can control, it can destroy cells and harm the body, and it can even incite an over-zealous immune reaction that can cause other damage.

Not all viruses are harmful, and many don’t infect humans. But ones that do cause can cause COVID, flu, hepatitis, shingles, herpes, measles, colds and many other illnesses.

Often, the best defense against viruses are vaccines, which proactively guard against viruses by training our immune systems to ward them off. We have not yet developed vaccines against all viruses, but we also have an array of targeted drugs that work to treat specific viruses if we get infected with them.

Bacteria are larger and more complex than viruses. Unlike viruses, they are living organisms that can live and reproduce on their own.

The vast majority of bacteria don’t hurt us, and many – like the ones that live in our gut and help digest food – are helpful.

However, some can harm us by replicating too quickly in our bodies or producing harmful toxins. Some of the most common bacterial illnesses are urinary tract infections, skin infections, pneumonia, sepsis and meningitis.

Scientists developed antibiotics to kill bacteria. But they aren’t effective against viruses. And because bacteria can adapt over time, overuse of antibiotics has created more and more bacterial strains that resist treatment.

While bacterial and viral infections are different, they’re often related. For instance, people with severe cases of viral pneumonia – caused by viruses like the flu, RSV or SARS-CoV-2 – also often end up with a bacterial infection in the lungs or sinuses. That means doctors must not only treat the virus but also prescribe antibiotics for the bacterial infection.

James is executive vice president and chief medical officer of the Oklahoma Medical Research Foundation. Cohen, a marathoner, is OMRF’s senior vice president and general counsel. Send your health questions to contact@omrf.org.