When Is the Best Time to Get a Flu Shot?
Oct 12, 2016
Every year, some of the same questions and concerns about season influenza and flu vaccination make the rounds on social media. So far this season, we’ve been hearing a lot of questions regarding the appropriate timing of a flu vaccination. Some people have mistakenly been advised to delay vaccination until November. Experts agree the best time to get a flu shot is now and here’s why:
When is flu season?
The CDC states,
“While seasonal influenza (flu) viruses can be detected year-round in the United States, flu viruses are most common during the fall and winter. The exact timing and duration of flu seasons can vary, but influenza activity often begins to increase in October. Most of the time flu activity peaks between December and March, although activity can last as late as May.”
When is the optimal time to get a flu vaccine?
In recent years, initial shipments of influenza vaccine have begun to arrive at some providers as early as July. Since this is well ahead of the typical onset of flu activity, many people have questioned when it is appropriate to start vaccinating for flu.
It makes sense that vaccination should occur before the onset of influenza activity. However, since no one can predict when influenza viruses may start circulating in any particular area, the Advisory Committee on Immunization Practices (ACIP) recommends that everyone over the age of 6 months should be vaccinated by the end of October, when it’s most common for flu activity to begin.
It’s important to understand that if can take up to 2 weeks from the date of vaccination for most people to generate vaccine induced immunity. Additionally, children aged 6 months through 8 years, who have not been vaccinated in previous years, will require 2 doses of flu vaccine before they are optimally protected. Therefore, they should receive their first dose as soon as possible after the vaccine becomes available, and the second dose at least 4 weeks later.
While vaccination by the end of October is recommended, the CDC is clear to state that October is not a cut-off. Vaccination should continue as long as influenza activity persists because the duration of the season can vary. For instance, a vaccine administered in December or later can still be beneficial since influenza activity can often last well into April or even May.
But wait….why are some people suggesting we wait to vaccinate?
A recent CNN article inaccurately suggested that people wait to get a flu shot until later in the season, explaining “the start of flu season is still weeks – if not months – away”. The suggestion has been repeated in other media, which is contributing to the public’s confusion regarding the preferred timing of flu vaccination.
Unfortunately, no one – not even CNN – can predict the “start” of flu season. In fact, just two days after CNN published their article, CDC Director Dr. Tom Frieden explained that the CDC had already tested 5,000 viruses and had begun to identify flu activity in the U.S. He made this statement on September 29th at a press conference held by the National Foundation for Infections Diseases (NFID). At the conclusion of the conference Dr. Frieden joined various flu experts in getting vaccinated and encouraging others to do the same.
CNN has also stated that the “marketing of the (flu) vaccine has become an almost year-round effort, beginning when the shots become available in August and hyped as long as the supply lasts, often into April or May”. They went on to claim that “the rise of retail medical clinics inside drug stores over the past decade — and state laws allowing pharmacists to give vaccinations — has stretched the flu-shot season.”
While CNN may be critical of the marketing of flu shots, the fact is that the CDC encourages people to get vaccinated for as long as the flu is circulating. By offering flu vaccines throughout the season, retail medical clinics are actually improving vaccination access which can help increase vaccination rates and potentially reduce the dangerous outcomes that can accompany the flu.
Dr. Tom Frieden has stated,
“If we could increase influenza vaccination coverage by just 5%, we would prevent 800,000 illnesses and almost 10,000 hospitalizations.”
Unfortunately, flu vaccination coverage during the 2015–16 flu season was only 45.6% among all people 6 months or older. Based on these numbers, it will take more than just flu shots being offered in pharmacies to impact either the length or severity of the flu season.
There are additional benefits to having retail medical clinics offering flu vaccination before flu activity is notable in our communities. First, it is not uncommon for people to need multiple reminders before taking action, and second, having the option to vaccinate in August can help parents ensure their college students get vaccinated before they arrive on campus.
Will protection from the flu shot wear off if I get it too early?
Some concerns have been raised about the possibility that very early vaccination of adults, particularly the elderly, might contribute to reduced protection later in the season. The challenge here is that the studies conducted to date have not provided consistent observations across age groups and seasons. Several observational studies have reported decreased vaccine protection within a single season, particularly against a particular influenza strain like A(H3N2). Other studies have noted a more pronounced decline in protection among older adults. However, it’s quite possible that these observations could be attributable to other factors or a combination of factors, such as drifted variants of flu strains over the course of the season.
The fact that waning immunity may occur is not necessarily debated, but waning immunity does not justify delaying vaccination.
While CNN suggests that “delaying vaccination might permit greater immunity later in the season,” the problem lies with the risk of flu infection before obtaining vaccine induced immunity. Even a lesser amount of protection late in the season seems preferable to no protection early in the season. Delaying vaccination until flu season is in full swing means we will miss opportunities to protect some of our must vulnerable people, such as young children, pregnant women, people with chronic health conditions and adults age 65 years of age and older. Sadly, the result may be dangerous or even deadly for some individuals.
In recent years, it’s estimated that between 71-85% of flu-related deaths and between 54-70% of flu-related hospitalizations have occurred among adults 65 years of age and older. Unfortunately, due to their aging immune system, older adults typically don’t have a strong immune response to flu vaccination. That is why there are two influenza vaccines designed specifically for people 65 and older.
One option is for adults 65 and over to request a high dose vaccine which contains four times the amount of antigen as the regular flu shot. With more than 50 million doses distributed in the U.S. since FDA approval in 2009, this vaccine has been shown to illicit a stronger immune response. Results from a clinical trial of more than 30,000 participants showed that adults 65 years and older who received the high dose vaccine had 24% fewer influenza infections as compared to those who received the standard dose flu vaccine.
The second option for those 65 years and older is the adjuvanted flu vaccine which is available for the first time in the U.S. this season. This vaccine is designed to help create a stronger immune response to vaccination. While there have yet to be studies comparing the efficacy of the high dose vaccine to the adjuvanted vaccine, a Canadian study of 282 people conducting during the 2011-2012 season found that this vaccine was 63% more effective than regular-dose flu shots among persons 65 and older.
While it’s likely that protection from either of these vaccines may still wane over time, it seems reasonable to expect better protection later in the season if immunity levels start off higher in the weeks following vaccination. On an NFID webinar last week, which specifically addressed flu vaccination among individuals 65 years of age and older, Dr H. Keipp Talbot, MD, MPH explained that waiting until November to get a flu vaccination is not advised, even for older adults.
When is it too late to get a flu vaccine?
As long as flu viruses are circulating, it’s never too late to get vaccinated. Early immunization is the most effective, but getting vaccinated in January or beyond could still protect someone for the remainder of the flu season, which has been known to extend into May. In fact, during the 2015-1016 season, there were several pediatric deaths that occurred as late as May and one as late as June. Just a few weeks ago, Shot of Prevention shared the story of a previously healthy woman in her mid 40’s who died as a result of flu infection in the Spring of 2016. The point is the flu is unpredictable and it’s best to be prepared before any possible chance of exposure.
Take some time to find out what’s new with flu for 2016-2017 and get answers to frequently asked questions about the upcoming season here.
If you haven’t gotten your flu shot yet, make plans to get yourself and your family vaccinated today. Contact your healthcare provider or check out the HealthMap Vaccine Finder to find out where you can locate flu vaccines in your area.
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