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Fact Check: Can You Still Catch COVID-19 Even If You Are Fully Vaccinated?


Dr. Alfredo Carpineti


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

Alfredo (he/him) has a PhD in Astrophysics on galaxy evolution and a Master's in Quantum Fields and Fundamental Forces.

Senior Staff Writer & Space Correspondent

Image Credit: Prostock-studio/

Vaccinations save lives. Image Credit: Prostock-studio/

Now that COVID-19 vaccinations are being rolled out in many countries, lockdown restrictions are being eased, including mingling in large crowds and not having to wear a mask. In the US, the Centers for Disease Control and Prevention (CDC) has changed its guidelines so that fully vaccinated people are no longer required to wear a mask indoors, despite the rise of the more transmissible Delta variant in the US and the World Health Organization reiterating its own position that fully vaccinated people should still wear a mask.

Over the last several weeks, there has been a lot of discussion on "breakthrough infections", meaning catching COVID-19 despite being fully vaccinated. There also appears to be confusion on how cases keep increasing in countries that have vaccinations even though vaccines have been shown to be effective against the Delta variant, currently the dominant version of SARS-CoV-2.


So let's start first with the bad news. First and foremost, we are still in the middle of the pandemic no matter what some people and, importantly, some governments may say. Vaccination efforts globally continue to be limited, with many of the richest countries hoarding the vaccine, a move that might result in the emergence of a virus variant that is not effectively neutralized by current vaccines.

Herd immunity through vaccination

So far less than less than a quarter of the world population has been given at least one dose of a COVID-19 vaccine. Over 3 billion doses have been administered globally but only 0.9 percent of people in low-income countries have received at least one dose.

For the vaccines to effectively curb the spread of the vaccine, over 70 percent of a population needs to be fully vaccinated, and even this is a moving target and depends on the variants. Not even in countries such as Israel (57.1 percent), the UK (49.3 percent), or the US (47.2 percent) has this been achieved yet. The good news is that the vaccines continue to provide protection against all the known variants of SARS-CoV-2, especially the Alpha and Delta variants.


Vaccines are not 100 percent effective but they are vital

But no vaccine is 100 percent effective especially as the emerging variants have become more dangerous and better at spreading. So, breakthrough infections that get past a vaccinated immune system are possible. One can be fully vaccinated and still catch COVID-19. However, the vast majority of COVID cases in vaccinated people are milder than in unvaccinated people and less likely to end in hospitalization.

Although death rates are very low for fully vaccinated people, they can occur. As David Spiegelhalter and Anthony Masters explain brilliantly in the Guardian, "Consider the hypothetical world where absolutely everyone had received a less than perfect vaccine. Although the death rate would be low, everyone who died would have been fully vaccinated." 

Although the UK is currently seeing daily increases in infection cases, the vaccine appears to have delivered a substantial reduction in hospitalizations and deaths. According to the CDC, as of June 21, 150 million Americans are fully vaccinated and 4,115 patients were hospitalized or died from vaccine breakthrough cases. Over three-quarters of these were among people 65-year-old or older. 


These numbers are likely destined to increase, and for this reason, it is important to continue to look at the infection rate between vaccinated and unvaccinated people. If we only look at the number of COVID cases reported, we do not see the full picture.

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