A question I continue to get: “Why should I get the Covid-19 vaccine? I’ve already had Covid, so I’m immune.”

And that query’s sister question: “Why should I get the vaccine? If I get Covid, my chances of dying are very low, and once I have the virus, I’ll be immune.”

Let’s first tackle the belief that illness confers dependable immunity. If only that were true. You do develop immunity after infection, but how long it lasts and how robust it is varies considerably. You absolutely can be reinfected; that’s indisputable.

Some good news: Research from the Centers for Disease Control and Prevention (CDC) and the Kentucky Department for Public Health has indicated that if you opt for vaccination after having Covid, your chances of reinfection drop dramatically. Of some 250 people who had tested positive for Covid, those who chose not to get vaccinated against the disease once they recovered were almost two-and-a-half times more likely to get Covid again than those who decided to get the shot. The findings pertain to the Delta variant, and while it’s too early to know how they will hold up with Omicron, researchers are hopeful that the outcome will be similar for those who have been vaccinated against Covid.

Still, many people continue to believe they can skip vaccination. Here are two of the arguments they give—and why they don’t hold up:

1. If I’ve had measles or chickenpox, I don’t need to get vaccinated. The immunity from those infections is as good as, if not better than, a vaccine.

That’s true. If you’ve had measles or chickenpox, the chances are nil that you will get these diseases again. But if you’ve had, say, mumps, the immunity is not permanent. Same for diphtheria, tetanus, and whooping cough. (That’s why we must get boosters for those.) What this means is that the immune system reacts differently to different pathogens. Not all infections guarantee lifetime immunity once you’ve had them—and all the data suggest that Covid falls into the category of not conferring lifelong protection.

2. I can just go for an antibody test. If my antibody level is high enough once I’ve had Covid, I’m one of the people who can’t get reinfected.

We do not know what constitutes a “high enough” antibody level. With something like chickenpox or measles, yes, a lab knows what number to look for because it has been shown that anything above that level correlates with protection from disease. Not so with Covid. While we are getting closer to understanding what type and level of antibodies correlate with protection, we are not there yet. There is no commercially available reliable laboratory test right now to answer the question: “Am I immune to future infection?”

Even if it were clear what constitutes a protective level of antibodies, antibody tests are not terribly reliable. There are false positives and false negatives. Plus, there are no standardized results; different tests yield different numbers.

So now you know why you should be vaccinated against Covid even if you’ve already had it. But what if you have dodged the Covid bullet so far? Many people have said to me they might as well skip the vaccine, get the disease, and be done with it since the risk of death is so low.

I understand the argument. Wearing the hat of a public health professional, I’m concerned with hospitalization and death rates. But wearing my human-being hat—my hat as a husband, father, grandfather, friend—I don’t want people to end up with any symptoms.

Both hats have me anxious. It’s true that on one level, the risk of death is low. More than 75 million Americans have tested positive for Covid since the start of the pandemic, and “only” 885,000 have died (as of early February), according to the CDC, which updates the numbers daily on its Covid Data Tracker website. I put “only” in quotation marks because 885,000 is quite a large number (and most epidemiologists believe the actual number is closer to 1.2 million). For perspective, there were about 3.4 million deaths in the U.S. in 2020, with Covid being the cause or contributing to nearly 380,000 of them. In 2020, Covid was the third leading cause of death behind heart disease and cancer.

But there are more reasons to go for vaccination against Covid than avoiding the risk of death:

• The illness you had may not have been Covid at all. Many people come down with Covid-like symptoms—fever, respiratory difficulties, fatigue—and assume they’ve had the disease without getting tested for it. But it very well may not have been Covid but instead the flu, for example, or RSV (respiratory syncytial virus). The symptoms of all three diseases can be the same. And coming down with something like the flu won’t protect you from Covid.
• Mild infection often does not confer significant immunity. A lot of people believe that no matter how mild their Covid symptoms are, they now have strong immunity from the disease going forward. That’s not necessarily true. There’s good evidence that a mild Covid infection in an unvaccinated person is not likely to be as protective as the immunity conferred by the vaccine. In other words, there’s no free pass.
• Whether symptoms are mild, severe, or even absent, you could infect other people. Unvaccinated people shed more virus for a longer period than vaccinated people who have a breakthrough infection. They are the primary drivers of this pandemic in the U.S. Consider that if you infect an unvaccinated person who is older or elderly, or a young child for whom vaccination has not yet been approved, or someone at higher risk of a bad outcome because of conditions like heart or lung disease, diabetes, or obesity, that person might not be able to mount a strong defense against the virus. So even if you survive, you might have passed along what for someone else could become a lethal infection.
• Not dying doesn’t mean you don’t suffer. Waiting to become infected with Covid because you probably won’t die leaves you open to long-term or possibly even lifelong health consequences—what’s now called long Covid—with such symptoms as brain fog, fatigue, body aches, lethargy, joint pain, digestive problems, ongoing shortness of breath, and loss of taste and smell. No one has a clear idea how long it takes for these symptoms to dissipate—or if they always do dissipate. So, while getting Covid may not kill you, it might leave you less able to function in your daily life and make you more dependent on others.

BOTTOM LINE: If you haven’t yet been vaccinated against Covid, do so now whether or not you’ve tested positive for the disease at any point of the pandemic. That way, you will substantially reduce your chances of dying or ending up hospitalized or with long Covid that could leave you with ongoing health problems. If you have been vaccinated and you are a candidate for the booster, please get it. Omicron is more capable of evading our immunity, and the booster adds significant protection against getting sick from it.