Fact check: COVID-19 and influenza vaccines too different to be directly compared 

Social media users have been sharing a meme which seeks to undermine COVID-19 vaccinations by casting doubt on whether it is possible to make a 95% effective coronavirus vaccine in 10 months, when the flu vaccine has been worked on for 70 years and is still only 40% effective. However, the two vaccines are different and cannot be directly compared. First, the vaccines are targeting different viruses as, although the flu and COVID-19 share some common symptoms, they are caused by different viruses. Second, the flu vaccine has to combat several influenza viruses which mutate whereas the COVID-19 vaccine targets just one virus. Third, there has been an unprecedented global and collaborative effort to advance the development of the COVID-19 vaccine.

Reuters Fact Check. REUTERS

The meme, shared hundreds of times on Facebook ( here  ,  here  ,  here  ,  here ), shows a picture of Bill Gates holding a vaccine with his face painted like the supervillain “The Joker” and says, “Do you honestly believe that in 70 years of research and development we have a 40% effective flu shot but in 10 months a 95% effective Rona shot?”

At the time of publication. over 1.5 million people worldwide and over 282,000 people in the United States have died of COVID-19, according to a Reuters tally (here). COVID-19 infections in the United States were at their peak at the beginning of December 2020 with a daily death toll of over 2,000 (here).

Reuters has previously debunked claims comparing the COVID-19 vaccine to other vaccines (here) and other claims related to the flu vaccine and coronavirus ( here  ,  here ). 


COVID-19 and influenza are both contagious respiratory illnesses and share some symptoms but they are caused by different viruses (here).

They both share symptoms such as coughing, fever and tiredness. However, COVID-19 can also cause changes to sense of taste and smell, and seems to cause more serious illness in some people (here).

Influenza is caused by four types of influenza viruses, types A, B, C and D. Influenza A and B viruses such as H1N1 and H3N2 cause seasonal epidemics of the disease (here)). COVID-19 is a new disease caused by a novel coronavirus SARS-CoV-2 that has not been seen before in humans (here).


Multiple flu viruses usually circulate during one season. As such, the seasonal flu vaccine protects against three or four different flu viruses. In the United States, these are usually an influenza A (H1N1) virus, an influenza A (H3N2) virus, and two influenza B viruses in the vaccine (here).

Which influenza viruses the vaccines protect against is decided by research and surveillance predicting which will likely be the most common during the upcoming season (here). However, as the CDC explains, flu viruses are constantly changing so it is not possible to predict this with certainty (here). To make this task more difficult, experts have to choose which viruses to include in the vaccine many months in advance for the vaccine to be produced and delivered on time.

The CDC says that while the flu vaccine effectiveness can vary, studies show that it reduces the risk of flu by 40% to 60%. The effectiveness depends on the age and health status of the vaccine recipient and the degree of match between the vaccine and the flu strain encountered ( here  ,  here ). When one or more of the circulating viruses are different from the vaccine viruses, vaccine effectiveness is reduced.

The COVID-19 vaccine is targeting SARS-CoV-2 (here). Initial research suggests that there are at least six strains of SARS-CoV-2 but that the mutation rate is low and the virus shows little variability, making it easier to develop a vaccine ( here  ,  here ).

Final vaccine trial data showed that the COVID-19 vaccine produced by Pfizer Inc and German partner BioNTech SE was 95% effective with no serious side effects (here). Full results from a late-stage study showed that Moderna Inc’s coronavirus vaccine was 94.1% effective with no serious safety concerns (here).

Britain’s AstraZeneca has announced an average efficacy rate of 70% for its vaccine and as much as 90% for a subgroup of trial participants who received a half dose first, followed by a full dose (here).

As of Dec. 2, 51 COVID-19 vaccines were in clinical evaluation, according to World Health Organization (WHO) data, and as of Nov. 24, five (including the three detailed above) were in large-scale phase 3 clinical trials for use in the U.S. ( here  ,  here  ,  here ).

The first round of vaccinations is expected to be administered in the United States as soon as the COVID-19 vaccines are approved by the U.S. Food and Drug administration, which will review Pfizer’s trial data on Dec. 10 and Moderna’s on Dec. 17 (here).

Pfizer’s trial involved over 43,000 people; 170 people contracted COVID-19 but 162 of these received a placebo (here). In the Moderna trial, more than 30,000 people were involved; 196 volunteers got COVID-19 but of these 185 had received a placebo (here).


Vaccines have to go through a number of stages before they are approved (here).

Scientists have managed to develop an effective vaccine for seasonal flu, but it needs to be renewed each year. This is because the body’s immune protection from vaccination declines over time and influenza viruses are constantly mutating, so new vaccines are needed annually to match the new strains ( here  , here ). As such, it is not correct to assert that scientists have been working on one single flu vaccine for 70 years.

In fact, a vaccine against one flu strain can be made in a shorter amount of time than it has taken to develop the COVID-19 vaccine because flu vaccine manufacturers can use the same process as for the annual seasonal flu vaccine. The coronavirus targeted by the COVID-19 vaccine is new and human coronaviruses do not yet have licensed vaccines or processes to build on (here). Scientists have been able to draw on some knowledge gathered from the development of animal coronavirus vaccines (here) and from early vaccine research for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), which are caused by coronaviruses closely related to SARS-CoV-2 (here).

However, this has not slowed progress because there has been a huge global effort to pool resources in order to accelerate the development and production of the COVID-19 vaccine (here).

In April 2020 the Access to COVID-19 Tools (ACT) Accelerator (here) was launched by the WHO and partners, bringing together governments, scientists, businesses, civil society, philanthropists and global health organizations to support the development and distribution of tests, treatments and vaccines. Operation Warp Speed has also been set up in the United States to invest in and coordinate vaccine efforts in order to help make and deliver COVID-19 vaccines as quickly as possible (here).

As the WHO explains, in the case of COVID-19, unprecedented financial investments and scientific collaborations have made it possible for some steps in research and development to happen “in parallel”. For example, they say that some clinical trials are evaluating multiple vaccines at the same time. The WHO points out that clinical and safety standards are maintained despite the acceleration (here).


Missing context. The influenza vaccine is less effective and has to be redeveloped each year because the vaccine targets multiple influenza viruses that are constantly mutating, whereas the COVID-19 vaccine is targeting one coronavirus, albeit a novel one. There has also been a global effort to accelerate the development of the COVID-19 vaccine.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work  here  .