Why antibiotics have no effect on the coronavirus

The majority of respiratory illnesses adults contract, including the common cold, influenza and COVID-19, are viruses and should not be treated with antibiotics, clinicians say. In fact, doing so will likely cause more harm than good.

“When typical working-age adults ages 19-60 who are generally healthy get a sudden respiratory illness where there is no evidence of pneumonia, the vast majority have a viral infection that is not helped by antibiotics,” said Dr. Harry Schrager, an infectious disease physician at Newton-Wellesley Hospital.

This is because antibiotics target bacteria, not viruses that are often at the root of respiratory illnesses.

What’s the difference?

“Both bacteria and viruses can cause illness, but bacteria are independent life forms that can replicate on their own, while viruses depend on a living host for life and most often multiply by hijacking our own cells,” Schrager said.

Bacteria can cause infections such as staph infections, strep throat, peptic (stomach and small intestine) ulcers, urinary tract infections, meningitis and pneumonia, while viruses can cause conditions such as measles, hepatitis, HIV, shingles and chickenpox as well as the common cold, influenza and the common seasonal and pandemic coronavirus. Vaccines have been developed for some viruses, and specific anti-microbial drugs that target viruses called antivirals for others. Researchers are working hard to develop a vaccine that will be effective for SARS-CoV-2, the coronavirus that causes COVID-19 illness, as there is for measles, and effective antiviral drugs, as there are for HIV, but currently there is no universally established treatment for COVID-19.

Because of the innate differences in bacteria and viruses, clinicians use different medications to treat them.

“The goal of an antibiotic is to kill bacteria, while the goal of an antiviral is really to stop the virus from replicating,” said Dr. Ashley Yeats, vice president of medical operations at the not-for-profit Blue Cross Blue Shield of Massachusetts, and a former emergency department physician. “If bacteria are like a house, antibiotics go into the house, tear down the walls, smash in the roof, flood the basement and take out the furnace in order to destroy it. Viruses are like copy machines that use RNA to replicate. Antivirals essentially jam the copier to stop the virus from replicating.”

Because bacteria and viruses differ, “You cannot use a medication designed for one to treat the other,” Yeats said. “It’s like trying to treat high blood pressure with insulin or taking blood pressure medication for diabetes. It won’t work.”

The tricky part, clinicians say, is that often the symptoms of a viral infection can mimic those of a bacterial infection. For instance, a sore throat can be caused by the streptococcal bacteria or a virus; similarly, sinus pain and pressure can be caused by bacteria or a virus.

But most often, it’s a virus.

In addition, common mild to moderate acute bacterial sinus infections also resolve without antibiotic treatment without complications.

Your physician likely won’t prescribe you an antiviral medication, either, because there are no effective antiviral medications for the common cold: “For almost every antiviral we make, the virus tries to get around it,” Schrager said.

While some patients believe antibiotics help them recover quicker regardless of the type of illness they have, Schrager said, often it’s not the antibiotics but instead because “they are on their way to getting better anyway because of their body’s own immune response.” He added that multiple studies have shown that many patients with common respiratory bacterial infections get better at about the same rate without antibiotics as they do with them and with fewer side effects.

Negative consequences

Overuse of antibiotics for treating illnesses can have negative consequences on individual patients – and our health ecosystem.

On an individual level, antibiotics often have unpleasant and potentially risky side effects: “Some antibiotics can lead to diarrhea and dehydration, which in infants can be very harmful and is a leading cause of death among infants in the developing world,” Yeats said.

In addition to killing harmful bacteria that make you sick, Yeats says antibiotics also kill off “good” bacteria that exist throughout the body and help to maintain balance, particularly in areas such as our gut and digestive tract. “The body is healthy when we have a diversity of bacteria living on the linings of our digestive, respiratory and genito-urinary tracts,” Schrager says.

More dangerously, antibiotic overuse leads to the rise of antibiotic-resistant bacteria, also known as superbugs, such as Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C.Diff), which can develop when bacteria learn to “outsmart” a particular antibiotic and grow stronger because of it. “Bacteria can evolve and become resistant to the antibiotics once used to treat it,” Schrager says. This is hazardous because we need ever more powerful antibiotics to fight the ever stronger bacteria, which have been shown to spread globally through travel and food production.

The best thing you can do to avoid the negative consequences of antibiotic overuse, Yeats says, is to ask questions. If your physician does prescribe an antibiotic, Yeats recommends asking why they believe you do not have a viral illness, what side effects you can expect, and whether the illness is likely to resolve without an antibiotic.

Unless a clinician determines you have a specific condition requiring antibiotics, Schrager said, “in general, most of us are better off without them.”