The Oddities of the 2022-23 Flu Season
Although flu cases are on the rise in some parts of the country, the Centers for Disease Control and Prevention (CDC) declared the 2022-23 flu season over. This season saw some oddities, including an unusually early start and the absence of a second wave. Experts speculate that this was due to a combination of factors, including effective vaccines and well-matched flu strains. Here are the key takeaways from the season:
Unusual Early Start to Flu Season
The Walgreens Flu Index began tracking flu activity earlier than usual, with the first cases in August. This was due to people returning to pre-pandemic activities, spending more time indoors without masks or social distancing, and becoming more vulnerable to respiratory infections.
No Second Wave
It is not unusual to see a surge in cases of influenza B later in the season, but this was not the case this season. According to surveillance data collected by Walgreens, it was the first time there was no second wave of flu. It is believed that this could be attributed to the effectiveness of the flu vaccines, which were relatively well matched with the circulating flu strains.
Experts believe that the vaccines available this season were well matched with the circulating flu strains. According to the CDC, the flu vaccine effectiveness against the predominant H3N2 viruses among children was 45%, which is higher than previous seasons.
Impact of Vaccines Among Adults
Adults aged 18 to 64 who received the flu vaccine were 51% less likely to have a flu-related hospitalization, according to the CDC. This highlights the essential role of flu vaccines in preventing severe illness and hospitalization.
Pre-Pandemic Burden of Disease
Despite the absence of a second wave, the illnesses, hospitalizations, and deaths from flu were largely in line with previous pre-pandemic seasons. The CDC estimates that, so far this season, there have been at least 26 million illnesses, 290,000 hospitalizations, and between 19,000-56,000 deaths from flu.
Flu Activity Peak by Month
The peak month of flu activity in the US has varied throughout the years, with February being the most common peak month and December the least common. However, with the start of the COVID pandemic, the timing and duration of flu activity have become less predictable.
CDC’s Flu Surveillance System
The CDC’s FluView interactive tool allows researchers and health experts to track the progress of flu season by monitoring influenza activity, tracking patterns of influenza-related illness, and measuring the impact of influenza on hospitalizations and deaths in the US.
Five Categories of Information Collection
Information in five categories is collected from nine different data sources, including state and local health departments, public health and clinical laboratories, vital statistics offices, healthcare providers, and clinics and emergency departments. This allows the CDC to determine what types of influenza viruses are circulating, detect changes in influenza viruses, and track patterns of influenza-related illness.
The Lag Between Collection and Reporting of Data
There is a week-long lag between when influenza surveillance data is collected and when it is reported. This is due to a reporting week that starts on Sunday and ends on the following Saturday. Each surveillance participant is required to summarize the weekly data and submit it to the CDC by the following Tuesday afternoon. The data are then downloaded, compiled, and analyzed at the CDC, with the FluView and FluView Interactive being updated on the following Friday.
Other Respiratory Viruses that Circulate During Flu Season
Influenza viruses are not the only respiratory viruses to spread during flu season. Other viruses include the rhinovirus, respiratory syncytial virus (RSV), human parainfluenza viruses (HPIV), human metapneumovirus (HMPV), respiratory adenoviruses, and human coronavirus.
The 2022-23 flu season was marked by some oddities that have not been seen before. Although cases were on the rise in some parts of the country, flu season as the CDC generally defines it was over. Despite an unusually early start and the absence of a second wave, illnesses, hospitalizations, and deaths from flu matched up with pre-pandemic seasons. The available flu vaccines were well matched with circulating flu strains, and flu vaccination remained instrumental in preventing severe illness and hospitalizations.
1. Are flu cases still being reported?
While flu season as the CDC generally defines it is over, some parts of the country are still reporting flu cases, indicating that the virus is still circulating in some regions.
2. How do flu vaccines work?
Flu vaccines work by triggering an immune response in the body. They contain small amounts of weakened or inactivated viruses that resemble the flu virus, which helps to stimulate the immune system to produce antibodies and fight off the virus.
3. Who is at high risk of severe illness from the flu?
People at high risk of severe illness and hospitalization from the flu include young children, pregnant women, adults over the age of 65, and people with underlying health conditions such as diabetes, heart disease, or weakened immune systems.
4. How can I protect myself from the flu?
The CDC recommends getting a flu vaccine every year as the first and most important step in protecting against the flu. Other preventative measures include frequent hand washing, avoiding close contact with people who are sick, and covering coughs and sneezes.
5. Can the flu and COVID-19 be present at the same time?
Yes, it is possible to be infected with both the flu and COVID-19 at the same time. The symptoms of the flu and COVID-19 can be similar, so it’s important to get tested for both if you are experiencing symptoms.