How can excess deaths be higher in 2021 than 2020 if vaccines had any benefit?

This is a good question I see many ask.

Some conclude from this question that vaccines must have been completely ineffective, or perhaps even have made things worse.

In this blog post, I will show that this is not the contradiction that it appears to be.

If you look at the available data and studies and think through the various relevant factors, it is clear that the following are simultaneously true:

1. Excess deaths in the world were higher in 2021 than 2020

2. Vaccines were highly effective in reducing risk of covid death, the primary driver of excess deaths.

3. The excess deaths in 2021 would have been MUCH WORSE had there not been covid vaccines.

The key factors I will highlight in this post include:

1. Far more people were exposed to COVID-19 in 2021 than 2020

2. In most places, the strict containment measures of 2020 were lifted in 2021

3. The variants emerging in 2021 were demonstrably more transmissible than those in 2020

4. The vast majority of people in the world were unvaccinated for most of 2021

5. Vaccines were highly effective in 2021, but not perfect.

1. Far more people were exposed to COVID-19 in 2021 than 2020

While the pandemic first emerged and was most disruptive in 2020, relatively few people were actually exposed to SARS-CoV-2 in 2020.

Below are plots of confirmed COVID-19 cases over time in the world from Our World in Data

We see that only 1% (10k per 1m) of the world had confirmed COVID-19 cases in 2020, while another 2.5% (25k per 1m) had confirmed COVID-19 cases in 2021.

So we see 2.5x more confirmed COVID-19 cases in 2021 than 2020, with 2021 a full pandemic year and 2020 only a partial pandemic year.

Of course, most SARS-CoV-2 infections are not formally documented as confirmed cases, so more than 1% were exposed to SARS-CoV-2 in 2020.

Serology studies from around the world provide more information about what % were exposed to SARS-CoV-2.

Serology tests measure SARS-CoV-2 antibodies in the blood to measure whether an individual shows evidence of exposure to SARS-CoV-2, whether or not they were ever documented as a confirmed case.`

Bobravitz et al. (2021) published a meta-analysis of 968 serology studies with >9 million participants from 74 countries all over the world.

They found that the median seroprevalence ranged from 0.6% in East Asia to 19.5% for Sub-Saharan Africa, with high-income countries including Western Europe and the USA having median seroprevalence 4.1%.

Seroprevalence studies are notoriously difficult to conduct to get unbiased estimates of population exposure, but this study makes it clear that the VAST MAJORITY of people in the world were not exposed to SARS-CoV-2 in 2020.

2. In most places, the strict containment measures of 2020 were lifted in 2021

Part of the reason so few were exposed to SARS-CoV-2 in 2020 was the strict containment measures in place over much of the world including travel restrictions, stay at home orders, and business closures.

In most places, these were heavily relaxed or lifted in 2021, partially motivated by the vaccine rollouts that were occurring.

The opening of countries to travel, lifting of restrictions, and the return of many to work and business led to greater opportunities for viral exposure, and helped accelerate the spread of the virus.

3. The variants emerging in 2021 were demonstrably more transmissible than those in 2020

In 2021, we learned that SARS-CoV-2 was evolving, and natural selection was guiding the evolution to more transmissible variants.

The dominant variants in 2021 (Alpha, Beta, Delta) were proven to be substantially more transmissible than the variants circulating in 2020, accelerating the spread of the virus around the world.

Also, the Delta variant that emerged appeared more virulent, with higher rates of hospitalization and death than previously circulating variants.

So these three factors:

1.  Increased exposure to SARS-CoV-2 as the virus spread more expansively across the world

2. Relaxation of strict containment measures

3. Emergence of more transmissible and possibly more virulent variants

all created an environment for far greater COVID-19 cases all over the world, a fraction of which would lead to deaths, leading to an increase of excess deaths.

But what about vaccines? 

Weren't they supposed to stop COVID-19 and prevent all deaths?

Since 2021 is when vaccines were rolled out, why didn't they prevent this surge of COVID-19 and the accompanying excess deaths?

4. The vast majority of people in the world were unvaccinated for most of 2021

While it is true that vaccines were rolled out all over the world in 2021, they were not all instantly given to the entire population on January 1, 2021.   

Many did not get vaccinated at all in 2021, and the vast majority of those who did got vaccinated later in the year, so the vast majority of individuals remained unvaccinated for most of 2021.

Below is a plot from OWID showing percent of world population receiving at least one dose of SARS-CoV-2 vaccine in 2021.

Note that almost 50% remained unvaccinated at the end of 2021.

Also note that most were vaccinated in the second half of the year, with barely 10% vaccinated at the beginning of June and barely 40% at the end of August.

We see that a majority of the world had no protection from vaccination throughout the 2021 COVID-19 waves, and the vast majority were unprotected for the COVID-19 waves in the first half of the year.

Thus, even with a 100% effective vaccine, we would have seen high levels of morbidity and mortality from COVID-19 in 2021, leading to high number of excess deaths.

And of course the vaccines were not 100% effective.

5. Vaccines were highly effective in 2021, but not perfect.

In their clinical trials, various SARS-CoV-2 vaccines demonstrated 80-95% efficacy in reducing the risk of symptomatic COVID-19, with the mRNA vaccines having the highest efficacy, viral vector vaccines the next highest, and inactivated virus vaccines the lowest efficacy.

Many dozens of real-world observational studies were done, and validated that in the first half of 2021, the effectiveness of vaccines vs. symptomatic infection was indeed high, between 60-90%, again highest for the mRNA vaccines, and even higher vs. severe or fatal COVID-19.

In the second half of the year, these studies revealed that as antibody levels waned about 6 months after vaccination, the effectiveness of mRNA vaccines vs. infection decreased down to 25-70%, but the effectiveness vs. severe/fatal disease was more robust, remaining at 80-95%.

Again, for the viral vector and inactivated virus vaccines, effectiveness was a bit lower.

Once Omicron variants emerged in 2022, the vaccine effectiveness numbers decreased even more, but this does not affect the discussion in this thread dealing with 2021.

In spite of the fact that it was clear that vaccines were not "perfect",  the clinical trials and many dozens of real world studies clearly demonstrated that vaccines were highly effective in 2021, especially against severe and fatal COVID-19.

Conclusion

So, we see that there were numerous factors in 2021 that led to people having far higher exposure to SARS-CoV-2 than in 2020, to variants that were more transmissible (and perhaps virulent), and with fewer containment measures in place.

Given most had not been exposed to SARS-CoV-2 in 2020, the population was highly vulnerable to COVID-19 and so the setting was ripe for much greater COVID-19 and excess deaths in 2021 than was seen in 2020.

All data and studies clearly show that vaccination greatly reduced the risk of COVID-19 disease and death among the vaccinated in 2021, but many in the world did not get vaccinated at all in 2021, and the majority of those who did got vaccinated in the second half of the year so remained unvaccinated during the COVID-19 waves earlier in the year.  Also, the vaccines were not 100% effective of course.

Under these conditions, it is wholly unsurprising that excess deaths increased in 2021 relative to 2020. 

However, given the overwhelming evidence vaccination substantially reduced the risk of COVID-19 deaths, the primary driver of excess deaths, it can be safely inferred that vaccines prevented a large number of excess deaths that would have occurred had vaccines not been available.

In summary, there were numerous factors that made COVID-19 worse in 2021 than in 2020, and while vaccines effectively mitigated risk, the lack of vaccine coverage and imperfection of the vaccines meant that this mitigation was not enough to make excess deaths lower in 2021 than they were in 2020.

But given all the data and studies, it is a safe inference to conclude the excess deaths would have been MUCH WORSE in 2021 in the counterfactual world where everything else was the same but with no COVID-19 vaccines.

While not covered here, there are similar factors why excess deaths remained high in many places in 2022, especially the first half of the year, and why in some countries (zero COVID countries), excess deaths were higher in 2022 than 2021 and 2020, with COVID-19 deaths still the primary driver of excess deaths throughout 2020-2022.