How long will the protection from vaccines last?

Biology/Immunity Vaccines

Q: How long will the protection from vaccines last? I just got my vaccine (yay!), when will I be at risk again?

A: Still TBD, but Pfizer just released data showing high protection for UP TO 6 months.

⚠️ NOTE: This does NOT mean ONLY 6 months, it means….AT LEAST 6 months!

Most scientists believe protection will last substantially longer.

We’re all anxious to know how long vaccine protection will last. But with a brand-new virus and new vaccines, we have to be patient while the earth makes a few more rotations around its axis.

The good news is that we are learning more each day, and the new Pfizer data gives us confidence that protection is NOT waning quickly. Key findings from this updated Pfizer Phase III trial data:

➡️ No safety concerns with at least 6 months follow-up for 12,000 vaccinated trial participants after their 2nd dose.
➡️ 927 confirmed symptomatic cases of COVID-19:
❇️ 850 cases in the placebo group
❇️ 77 in the vaccine group
❇️ = 91.3% vaccine efficacy up to 6 months after the second dose.
❇️ There were 32 cases of severe disease, as defined by the CDC, in the placebo group.
❇️ NONE in the vaccine group.
➡️ The vaccine was 100% effective in preventing COVID-19 cases in South Africa, where the B.1.351 lineage is prevalent (though this is from a small sample).

The awesome part about these data is that they measured ACTUAL protection from COVID-19, not just antibodies or other immune “correlates” of protection.

We don’t have similar data released yet for the other vaccine trials, but we expect a steady stream of new data as more time passes since the beginning of the trials.

➡️ What else do we know about how long immunity might last?

A recent study tested the blood over time of people naturally infected with SARS-CoV-2. They tested not only antibodies but other important components of immune response like B cells and T cells. They found that most people had strong signs of immunity up to 8 months after infection (which is as long as they observed people).

Since the vaccines are generally producing *stronger* immune responses than natural infection, this bodes well for the duration of vaccine-induced immunity as well.

Overall, there is no substitute for time in helping us learn the duration of immunity, and new variants *may* hasten the need for booster shots (although the vaccines are also performing well against variants so far). Seasonal coronaviruses that give us the common cold tend to have quickly waning immunity, but there is evidence that immunity against SARS-CoV-1 and MERS–which are more similar to SARS-CoV-2– is longer lasting.

Many scientists are hopeful that immunity from the COVID-19 vaccines could last for several years at a time, but likely AT LEAST one year. So it is unlikely that you will need to rush out for another shot soon.

Stay tuned as we accumulate more data…literally as the world turns!

Those Nerdy Girls

Further reading:

“You Got Your Shot(s). But How Long Will COVID-19 Vaccine Immunity Last?”

“Ongoing trial shows Pfizer Covid-19 vaccine remains highly effective after six months”

Pfizer Press release

“Coronavirus immunity lasts at least 8 months after infection, and perhaps even years, new research shows”

“Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection”

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