Leaky Vaccines

A perfect vaccine protects like a child’s immunity after chicken pox.  It prevents future disease, prevents transmissions to others, and lasts for a very long time.  Anything less is called a leaky vaccine.  Let’s see how our current COVID vaccines stand up to each of these points:

• Prevent Future Disease.  COVID vaccines don’t connect on this standard, and there are any number of reports that can show this.  Just to pick one we haven’t discussed before, read the MMWR Early Release for August 24, 2021 which shows vaccine effectiveness dropped from 91% to 66% since the arrival of the delta variant, suggesting that vaccine is less protective against delta than pre-delta strains.  But this data also shows that vaccine protection from disease was less than perfect even before delta.  A perfect vaccine has effectiveness of 100%; our COVID vaccines never have.
• Prevent Transmission of Virus to Others.  Another swing and a miss.  To drive this point home, we need go no further than the CDC’s Recommendations for Fully Vaccinated Individuals, which states, “Preliminary evidence suggests that fully vaccinated people who do become infected with the Delta variant can be infectious and can spread the virus to others.”  Still not convinced?  A recent pre-print study from Vietnam demonstrates transmission between vaccinated healthcare workers.  A perfect vaccine would prevent infection between vaccinated individuals; our COVID vaccines do not.
• Lasts for a Long Time.  Strike three.  Even though the vaccines have been available for less than a year, emerging data from Israel suggests that their effectiveness is already waning.  My own antibodies lasted for less than five months.  Vaccine-induced immunity doesn’t last very long.

Our COVID vaccines are leaky.  So what?  Just take a booster.  And another.  And another.

There are several problems with this reasoning.  Here are three:

First, a false perception of protection leads to risky behavior.  Maybe you’re young, and it doesn’t matter if you get a SARS-CoV-2 infection.   Maybe you’re pregnant or elderly, and it does.  When you believe that your vaccination protects you from future infection, you are more likely to ignore precautions that might protect your life, or the lives of others.   

Second, leaky vaccines may stimulate the formation of more dangerous variants.  The theory goes like this.  The virus seeks a host.  If vaccination reduces but doesn’t eliminate the available hosts, the virus feels evolutionary pressure to mutate into a form that will infect more people.  Not everyone agrees with this idea, but there is enough evidence to at least consider this possibility.

Finally, leaky vaccines will not eradicate SARS-CoV-2, no matter how many boosters you take.  Vaccination has eradicated exactly one human viral pathogen from the earth: smallpox.  The smallpox vaccine was a perfect example of a perfect vaccine.  It prevented disease.  It prevented transmission.  It lasted a lifetime. It eradicated the virus from the earth.  And it took nearly 200 years.  We cannot expect a leaky vaccine to produce the same results.

Maybe future vaccines won’t be as leaky as the ones we have now.  Maybe we’ll even have a perfect COVID vaccine someday.  We can hope.  But until then, eradication is a pipedream.  Instead, we must do all we can to protect the lives, the health, and the wellbeing of people while the virus is among us.  We must learn to live with the virus.