Has the Availability of the COVID-19 Vaccine Influenced the Immunization Coverage for Influenza, in Canada, England, and Australia, over the Last Three Years (2019-2021) before and after the Pandemic?

GABRIEL ORHADJE, ROMINA MOEINI (she/her), AKSHAY SENTHILKUMAR (he/him), MIRAL FATIMA

Calgary, AB

Third place at the Youreka Calgary Regional Symposium 2022

Edited by Karan Thakur

COVID-19, formally known as Sars-CoV-2, is a novel respiratory illness with numerous adverse economic, social, and political effects due to its high levels of transmissibility and virulence. On the other hand, influenza has been present in many geographical locations. Influenza has been less detrimental to the healthcare systems due to its lower levels of virulence and the establishment of influenza vaccinations in the mid-1900s. This study aims to identify if the immunization coverage of influenza, from 2019 to 2021, has been affected by the availability of COVID-19 vaccines in Canada, England and Australia. Precisely, to determine if the influenza vaccine uptake is significantly different after the distribution of COVID-19 vaccines in 2021 in the three chosen countries with a close-range of populations. This understanding is integral to determining the effect of COVID-19 relief implementation on humans' cognitive biases toward previously accepted treatment options for other conditions. The results indicate that the uptake of COVID-19 vaccines has significantly increased the uptake of influenza vaccines in the geographical areas analyzed. Further research on this relationship and COVID-19's effect on other medical conditions is recommended for future studies.

INTRODUCTION

Influenza, a highly contagious respiratory illness caused by the influenza virus, has created annual health burdens for years. The influenza A virus with the hemagglutinin (HA) and neuraminidase (NA) surface proteins are transmitted between humans (CDC.gov, 2022). The H1, H2, H3 and N1, and N2 subsections of the influenza A virus have most commonly caused widespread disease in the human population over the last decade (Canada.ca, 2022). As a result, many individuals have been routine with their fall influenza vaccine uptake. However, with the new COVID-19 pandemic and the continuously evolving health restriction starting on March 13, 2022, a significant amount of attention has been shifted to COVID-19. People have become routinely engaged with the immunization services, potentially influencing the influenza vaccine uptake. Social isolation and the health-mandated quarantine may also contribute to the change in influenza vaccine uptake. McMaster University has done similar research to explore the correlation between influenza vaccine and COVID-19 vaccine uptake. Their findings stated a positive association between the two uptakes and how an “individual’s concern about COVID-19 increases the likelihood of influenza vaccine uptake.” (Sulis, 2022). However, the study focused on pre-pandemic years 2015-2020, so the association between the two variables for 2019-2021 remains unexplored. This study aims to find whether the availability of the COVID-19 vaccine, in the population aged 12 and over has influenced and significantly changed the immunization coverage for influenza in Canada, England and Australia over the last three years (2019-2021) before and after the pandemic. Understanding of the possible effect that COVID-19 vaccine availability may have on influenza vaccine uptake, it is integral to determine the effect of COVID-19 relief implementation on humans' cognitive biases toward previously accepted treatment options for other conditions, namely influenza.

MATERIALS & METHODS

Influenza vaccine uptake data for Canada, England and Australia was analyzed. Analyzing data from countries with developing healthcare systems was avoided, as increases in vaccine uptake could be due to greater availability rather than relating to the pandemic. Data for the influenza vaccination uptake in Canada was collected from the Statistics Canada database (Canada.ca, 2022). In addition, the data for Influenza Vaccination uptake in Australia was taken from Australia’s Ministers of Department of Health (health.gov.au, 2022), and the data for England was collected from Public Health England database (NIH.gov, 2022). A paired t-test was used to analyze and compare the means between the influenza vaccine uptake within the 12 and older age group in 2019 and 2021. 2019 was considered as the year before the availability of COVID-19 vaccine and 2021 as the first year that COVID-19 vaccines were distributed. With the paired t-test, the replicates in each group were the number of the people vaccinated for the three selected countries, and the groups for this study were 2019 and 2021. The influenza vaccination data was measured as the number of individuals receiving influenza vaccinations per year in Canada, England, and Australia. All the data was amalgamated into a single spreadsheet and subsequently exported to R studio, where the statistical analysis was conducted. Based on the data, during 2019, there were about 10, 208, 700 people who received influenza vaccine in Canada, about 13, 200, 000 in Australia, and 25, 358, 940 in England. During 2021, these numbers changed to 15, 356, 000 in Canada, about 18, 000, 000 in Australia, and 29, 893, 320 in England.

At first, a normality test of the influenza vaccinations using a Shapiro-Wilk Test was conducted to determine the normal distribution of the uptake of vaccinations and if the analysis required a parametric or non-parametric statistical test. The Shapiro-Wilk test identified that the data was normally distributed, evidenced by a p-value of greater than 0.05. Hence, the null hypothesis that the data wasnormally distributed is not rejected. As a result, a paired t-test was conducted to determine if the influenza vaccine uptake is significantly different after the distribution of COVID-19 vaccines in 2021.

RESULTS

**Figure 1:** Box plot of the mean influenza vaccine uptake before and after the distribution of COVID-19 vaccines (2019 and 2021). Graph showing influenza vaccine uptake is significantly higher after the distribution COVID-19 vaccines in 2021. Uptake of influenza vaccine in the general population in England, Australia and Canada represented through a box plot from publicly available data.

**Figure 2:** Graph showing the paired data information of influenza vaccine uptake before (2019) and after (2021) COVID-19 vaccine distribution. Influenza vaccine uptake is significantly higher after the distribution of COVID-19 vaccines in 2021. Uptake of influenza vaccine measured through publicly available data and displayed across a scale representing influenza vaccine uptake before the distribution of COVID-19 vaccines and after the distribution of COVID-19 vaccines in 2021.

The graph of the box plot after the distribution of COVID-19 vaccines (2021) demonstrates a significant increase in the uptake of the influenza vaccine, compared to that of the influenza vaccine uptake before the COVID-19 vaccines were widely distributed. The median line of the box plot after the widespread distribution ofCOVID-19 vaccines (2021) is higher than the median line of the box plot of influenza vaccine uptake before the distribution of COVID-19 vaccines (2019-2020). The influenza vaccine coverage in individuals aged 12 and older, belonging to Canada, England, and Australia, was significantly higher in 2021 after the distribution of COVID-19 vaccines compared to the influenza immunization coverage before COVID-19 (2019). There was a considerable increase in influenza vaccine uptake recorded after the distribution of COVID-19 vaccines (2021).

**Table 1**: The p-value for the paired t-test and mean for year 2019 and 2021

A p-value of 0.001349 was obtained from the paired t-test that was conducted, analyzing the correlation between the influenza vaccine uptake and the distribution of COVID-19 vaccines in Canada, England, and Australia. The mean vaccine uptake data before COVID-19 (2019) is 16, 255, 880, whereas the mean of influenza vaccine uptake data after COVID-19 vaccines were distributed (2021) was 21, 083, 107. As the paired t-test resulted in a p-value less than 0.05, a relation exists between the distribution of COVID-19 vaccines and the uptake influenza vaccine in Canada, England, and Australia.

Based on the data, during 2019, there were about 10, 208, 700 people who received influenza vaccine in Canada, about 13, 200, 000 in Australia, and 25, 358, 940 in England. During 2021, these numbers changed to 15, 356, 000 in Canada, about 18, 000, 000 in Australia, and 29, 893, 320 in England.

DISCUSSION

With over 282.1 million COVID-19 vaccines distributed over Canada, England, and Australia within the last two years, all three countries boast extremely high COVID-19 vaccination rates (Our World in Data COVID-19 Vaccinations, 2022). However, has this widespread availability of COVID-19 vaccines across Canada, England and Australia affected the influenza vaccine uptake in individuals aged 12 and over in these countries? This study aimed to identify if an association exists between the widespread availability of COVID-19 vaccines in Canada, England and Australia, and the immunization coverage for influenza between 2019 and 2021.

The influenza vaccine coverage was significantly higher in 2021 after the distribution of COVID-19 vaccines compared to the influenza immunization coverage before COVID-19 (2019) in individuals aged 12 and older, belonging to England, Canada, and Australia. According to the data analyzed, COVID-19 vaccines started distribution in England, Canada, and Australia in late 2020 and were administered on a large scale throughout 2021. Data for influenza vaccine uptake across all three countries showed a considerable increase through 2020 and 2021, when the COVID-19 vaccines were also actively being rolled out. In the paired t-test that was conducted to analyze the difference and association between the two variables, a p-value of 0.001349 was received. As the p-value obtained through the paired t-test was less than 0.05, it can be understood that the association between the availability of COVID-19 vaccines across the three countries and the influenza vaccine uptake is statistically significant. The influenza vaccination rate after the distribution of COVID-19 vaccines was significantly higher than before COVID-19 vaccines were distributed (2019) in England, Canada, and Australia. Thus, there is evidence to suggest a positive influence on the influenza vaccine uptake in England, Canada, and Australia from the distribution of COVID-19 vaccines during the pandemic.

One limitation of the research is the unavailability of influenza vaccine data for 2022. Having the influenza vaccine uptake data for 2022 would have helped immensely in analyzing the association between the COVID-19 vaccine and the influenza vaccine uptake, in the year so far. This study adds to the current knowledge of the association between influenza vaccine uptake and the distribution of COVID-19 vaccines through 2021, which previous studies did not cover and remains largely unexplored. This study also helps in providing a more holistic view of the association between influenza vaccination rates across these three major countries and COVID-19 vaccine availability, as the most current data available to the public was analyzed.

Based on a study conducted by McMaster University in mid-2020, "among the 23,385 participants analyzed, influenza vaccination rate increased over time: 14,114 (60.4%) in 2015–2018 and 15,692 (67.1%) in 2019/2020." This similar research concluded that "to a lesser degree, those more concerned about COVID-19 were also more likely to report influenza vaccination in fall 2020" (Sulis, 2022). This research which focused on the years 2019 (pre-distribution of COVID-19 vaccines) and 2021 (after distribution of COVID-19 vaccine), also found this statistically significant increase in influenza vaccine uptake. In addition, in a research paper done through UK-wide Observational Study (NIH, 2022), stated that the "U.K. National Health Service (NHS) extended eligibility for influenza vaccination this season to approximately 32.4 million people (48.8% of the population)." The study aimed to see if the pandemic has influenced an increase in influenza vaccine uptake in England. Similar to the positive association, in the U.K. The NHS study found that "among the 6641 respondents, 945 (14.2%) were previously eligible but were not vaccinated; of these, 536 (56.7%) intended to receive an influenza vaccination in 2020-2021, as did 466 (68.6%) of the newly eligible respondents" (JMIR Public Health Surveill, 2021.)

It can be hypothesized that the existing cognitive bias around COVID-19 restrictions may have likely affected the willingness of individuals in certain populations to receive the vaccine against influenza. During the early stages of the pandemic, people may have been under the impression that social distancing and masking would protect them from the flu and prevent them from contracting influenza. Seasonal influenza viruses are believed to be transmitted from person to person primarily through virus-laden droplets that are spread when infected people speak, cough or sneeze. Restrictions like masking and social distancing may lower the chances of getting infected with influenza, as the droplets may not be able to be inhaled in large quantities due to masking and distancing. However, social distancing and masking do not entirely protect individuals from getting infected with the virus or prevent them from passing it to others. Influenza is a highly transmissible virus, and masking and social distancing measures are not considered highly effective at protecting one from the virus. The best way for individuals to protect themselves from the influenza virus is by getting vaccinated, which many people decided to do based on the data we analyzed, and even more individuals chose to get vaccinated with the ongoing pandemic. As many strains of the influenza virus may be passing from person to person, it is challenging to be completely protected from the virus by simply following COVID-19 restrictions. Influenza vaccines have proven to be highly effective by the CDC and are also extremely safe (U.S. Department of Health & Human Services, 2022).

An overall upward trend in the influenza vaccination rate in individuals aged 12 and older, belonging to Canada, England and Australia can be found, even after the distribution of COVID-19 vaccines. Some people may have opted to take the influenza vaccine due to the anxiety surrounding the COVID-19 virus in 2020 and 2021. Availability of the COVID-19 vaccine potentially influenced people to take the influenza vaccine to suppress symptoms due to the similarity of the symptoms between COVID-19 and influenza. However, these ideas are hypothetical, and there have been only a few studies investigating the effect of COVID-19 restrictions on the uptake of influenza vaccines in Canada. Another limitation in the research is that the possible impact of social anxiety due to COVID- 19 on influenza immunization coverage could not be directly analyzed.

The study could be improved by surveying the population in Canada, England, and Australia about why they received the influenza vaccine or why they did not. This is a future step that could help immensely in understanding the social aspect of the willingness of people to get the influenza vaccine, and it would provide a more holistic view of the association between COVID-19 vaccinations and influenza immunization coverage. In addition, as more data becomes available regarding the number of COVID-19 vaccination for future years, a linear regression can be used to model the two uptakes. This could more accurately state whether a correlation between the two uptakes exists over multiple years rather than an association only for the years 2019 and 2021.This study is significant due to its relevance in the today’s world as it aids society in gaining a better understanding of how individuals react to getting vaccinated against different diseases, disorders, and viruses in the event of a pandemic. Since flu and COVID-19 vaccination data from three countries were analyzed, a holistic and comprehensive understanding of the effects of pandemics and the availability of the other vaccines that may be offered to the population on a yearly or bi-yearly basis, can be gained. A strong association between the two variables can be found. This association between the COVID-19 vaccine availability and influenza vaccine uptake may help predict how individuals may react to a pandemic and the vaccine availability for the virus. This study holds significant value towards creating an improved resource planning for the distribution of COVID-19 vaccines and effective messaging to help get COVID-19 and Influenza vaccines to more people.

CONCLUSION

The data for influenza vaccine uptake showed a considerable spike in 2021, when the COVID-19 vaccines were actively being rolled out across the three countries. In the paired t-test that we conducted to analyze the difference between the two variables, a p-value of 0.001349 was obtained. As the p-value was less than 0.05, it can be understood that the association between the availability of COVID-19 vaccines across the three countries and the influenza vaccine uptake is statistically significant. This strong association between the COVID-19 vaccine availability and influenza vaccine uptake may help predict how individuals may react to a pandemic and the vaccine availability for the virus. The influenza vaccination rate after widespread COVID-19 vaccine distribution was much higher than before COVID-19 vaccines were distributed (2019) in Canada, England, and Australia. The study helps us as a society gain a better understanding of how people react during a pandemic, and it is essential for informing resource planning surrounding vaccination.

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