Some Vaccines Last a Lifetime. Here’s Why Covid-19 Shots Don’t.

Researchers have calculated a key number—the threshold of protection—for other vaccines. Covid-19’s is still a mystery.

Recent studies have shown that the effectiveness of Covid-19 vaccines is decreasing, though experts say the shots still work well. WSJ explains what the numbers mean and why they don’t tell the full story. Photo illustration: Jacob Reynolds/WSJ

Why don’t Covid-19 vaccinations last longer?

Measles shots are good for life, chickenpox immunizations protect for 10 to 20 years, and tetanus jabs last a decade or more. But U.S. officials are weighing whether to authorize Covid-19 boosters for vaccinated adults as soon as six months after the initial inoculation.

To Read the Full Story

Continue reading your article with
a WSJ membership

Resume Subscription

We are delighted that you'd like to resume your subscription.

You will be charged $ + tax (if applicable) for The Wall Street Journal. You may change your billing preferences at any time in the Customer Center or call . You will be notified in advance of any changes in rate or terms. You may cancel your subscription at anytime by calling .

Please click confirm to resume now.