Flu Vaccine Effectiveness
How effective is the flu vaccine, and will getting vaccinated reduce the severity of your illness even if the vaccine is a poor match to circulating influenza virus strains? While public health officials insist vaccination is the best way to prevent the seasonal flu, the evidence calls this assumption into question, and most health care professionals won’t even get the flu shot if it’s voluntary.1
In its 2014 meta-analysis2 of the available research on inactivated influenza vaccines, the Cochrane Collaboration (which is considered by many as the gold-standard for scientific meta-reviews), reviewed evidence related to influenza and influenza-like illness (ILI) that people experience during flu seasons and stated:
“Over 200 viruses cause ILI, which produces the same symptoms (fever, headache, aches, pains, cough and runny nose) as influenza. Without laboratory tests, doctors cannot distinguish between ILI and influenza because both last for days and rarely cause serious illness or death.
The types of virus contained in influenza vaccines are usually those that are expected to circulate in the following influenza seasons, according to recommendations of the World Health Organization (seasonal vaccine).”
The Cochrane researchers concluded that:
“Injected influenza vaccines probably have a small protective effect against influenza and ILI (moderate-certainty evidence), as 71 people would need to be vaccinated to avoid one influenza case, and 29 would need to be vaccinated to avoid one case of ILI. Vaccination may have little or no appreciable effect on hospitalizations (low-certainty evidence) or number of working days lost.”
If 71 people have to be vaccinated in order for a single case of influenza to be avoided, this means that flu shots have a rather abysmal effectiveness rating. And it isn’t surprising that flu shots have “little or no appreciable effect on hospitalizations or number of working days lost,” considering its ineffectiveness at preventing illness. Similarly, while many assert that getting vaccinated will render flu symptoms less severe — should it fail to protect you after all — there’s really no good evidence for this either.
Interim Estimates of Flu Vaccine Effectiveness Are In
On February 16, the CDC published interim estimates of the 2017/2018 seasonal influenza vaccine’s effectiveness for the U.S.3 Based on data from 4,562 children and adults enrolled in the U.S. Influenza Vaccine Effectiveness Network between November 2, 2017 and February 3, 2018, the CDC reports the overall adjusted vaccine effectiveness against “influenza A and influenza B virus infection associated with medically attended acute respiratory illness” was 36 percent. More precisely, vaccine effectiveness is estimated to be:
- 25 percent effective against the A(H3N2) virus
- 67 percent effective against A(H1N1)pdm09 viruses
- 42 percent effective against influenza B viruses
And many of these numbers were inflated due to poor study design.4
So what other natural and alternative options do we have for preventing and treating the flu?
Optimizing Vitamin D Effective During Flu Season
Studies have repeatedly demonstrated the excellent track record of vitamin D for preventing respiratory infections. Most recently, a 2017 scientific review5,6 of 25 randomized controlled trials found that vitamin D supplementation cuts rates of acute respiratory infections among all participants.
The studies included nearly 11,000 individuals from more than a dozen countries, and showed that people who regularly took vitamin D supplements were less likely to contract acute respiratory tract infections compared to those who did not take supplemental vitamin D. Those with blood levels below 10 ng/mL, which is a serious deficiency state, cut their risk of infection by half.
People with higher vitamin D levels reduced their risk by about 10 percent. According to this international research team, vitamin D supplementation could prevent more than 3.25 million cases of cold and flu each year in the U.K. alone.7 Another statistic showing vitamin D is a very effective strategy in preventing respiratory illness during the flu season is the NNT.
As mentioned at the beginning of this article, the Cochrane Collaboration concluded in 2014 that the NNT for the flu vaccine is 71. In this 2017 respiratory infection study, the NNT for vitamin D was 33, meaning one person would be spared from acute respiratory infection for every 33 people taking a vitamin D supplement.
Among those with severe vitamin D deficiency at baseline, the NNT was 4. If you’re going to gamble, which odds would you rather have — a 1 in 71 chance of being protected against respiratory infection, or a 1 in 33 chance (or 1 in 4 should you be severely vitamin D deficient)? In my view, optimizing your vitamin D levels is one of the absolute best respiratory illness prevention and optimal health strategies available.
Here is a great vegan vitamin D supplement to take on a daily basis, especially during the winter months when getting optimal sun in the middle of the day can be challenging.
Tamiflu or Quercetin?
Should you or your child get sick and a doctor or pediatrician recommends Tamiflu,8 please understand that this antiviral drug shortens the duration of flu symptoms by less than 17 hours.9,10 It also does not reduce viral transmission and does not lower your risk of complications, such as pneumonia.11,12
Some scientists have also warned that Tamiflu’s serious risks outweigh the benefits.13 These risks include convulsions, brain infections, psychosis and other neuropsychiatric problems.14,15 The drug is particularly risky for children, and more than half of all children taking Tamiflu suffer side effects from the drug.16,17
Considering Tamiflu’s risks and limited effectiveness, quercetin is safe and effective. Quercetin, a plant flavonol found naturally in apples, plums, red grapes, green tea, elder flower and onions, packs a powerful antiviral punch.18 Some of its mechanisms of action include inhibiting the ability of viruses to infect cells and inhibiting replication of already infected cells. A number of studies have confirmed quercetin’s effectiveness against viral infections, including the following:
|A 1985 study found quercetin inhibits infectivity and replication of herpes simplex virus type 1, polio-virus type 1, parainfluenza virus type 3 and respiratory syncytial virus.19|
|A 2010 animal study found that quercetin inhibits both influenza A and B viruses. Two other important discoveries were made. Firstly, the viruses were unable to develop resistance to quercetin and, secondly, when used concomitant with antiviral drugs (amantadine or oseltamivir), the effect was significantly amplified — and it prevented drug resistance from developing.20|
|A 2004 animal study investigating quercetin’s effect on influenza used a strain of the H3N2 virus. According to the authors:21
|In 2014, researchers noted that quercetin appears to be “a promising treatment for the common cold,” caused by the rhinovirus, adding that “Quercetin has been shown to reduce viral internalization and replication in vitro, and viral load, lung inflammation and airways hyper-responsiveness in vivo.”22
By attenuating oxidative damage, it also lowers your risk of secondary bacterial infections, which is actually the primary cause of influenza-related deaths. Importantly, quercetin increases mitochondrial biogenesis in skeletal muscle, which suggests part of its antiviral effects are due to enhanced mitochondrial antiviral signaling.
|A 2016 study found quercetin offered protection against influenza A virus H1N1 by modulating protein expression. More specifically, the regulation of heat shock proteins, fibronectin 1 and prohibitin was instrumental in reducing viral replication.23|
|A second study published in 2016 found quercetin inhibited a wide spectrum of influenza strains, including H1N1, H3N2 and H5N1. According to the authors, “This study indicates that quercetin showing inhibitory activity in the early stage of influenza infection provides a future therapeutic option to develop effective, safe and affordable natural products for the treatment and prophylaxis of [influenza A viruses] infections.”24|
Quercetin 3-O-glucodise (Isoquercitrin) Content in Other Foods
|Grapes, black (100 g)||2.17 mg|
|Red Raspberry, raw (100 g)||3.58 mg|
|Nectarine, whole (100 g)||0.11 mg|
|Broccoli, raw (100 g)||1.80 mg|
|Black tea, infused (100 ml)||
Prevention of Respiratory Infections Shouldn’t Be so Risky
This video highlights how adding in even just 1 serving of fruits or vegetables a day can dramatically increase our immune function and how certain plant foods, especially cruciferous veggies, are immune system powerhouses:
Aside from vitamin D and quercetin, maintaining good levels of vitamins B1 and C may go a long way toward keeping you healthy through the flu season and beyond. Influenza has also been treated with high-dose vitamin C,26 and vitamin C also boosts the effectiveness of quercetin. Taking zinc lozenges at the first sign of respiratory illness can also be helpful.
- 1 Washington Post February 28, 2018
- 2 Cochrane.org
- 3, 5 CDC.gov MMWR February 16, 2018; 67(6): 180-185
- 4 CDC, December 21, 2015 Influenza Vaccine Effectiveness: How Well Does the Flu Vaccine Work?
- 5 BMJ 2017; 356:i6583
- 6 NPR February 16, 2017
- 7 BBC.com February 16, 2017
- 8 Tenpennyimc.com Tamiflu
- 9 BMJ 2014;348:g2545
- 10 Forbes April 10, 2014
- 11 The Guardian April 10, 2014
- 12 Cochrane Database of Systematic Reviews 2014, Issue 4. Art. No.: CD008965
- 13 Newsweek January 15, 2018
- 15 Clin Psychopharmacol Neurosci. 2015 Aug; 13(2): 209–211
- 16 The Guardian July 31, 2009
- 17 Eurosurveillance July 2009; 14(30)
- 18 Life Extension February 2007
- 19 Journal of Medical Virology January 1985 DOI: 10.1002/jmv.1890150110
- 20 Antiviral Research 2010 Nov;88(2):227-35
- 21 Experimental Lung Research 2005; 31(5)
- 22 Journal of Infectious Diseases and Preventive Medicine May 24, 2014; 2: 111
- 23 Journal of Agricultural and Food Chemistry 2016; 64(21): 4416-4425
- 24 Viruses 2016 Jan; 8(1): 6
- 25 Phenol-Explorer, Database on polyphenol content in food, Food composition; http://phenol-explorer.eu/contents/polyphenol/293(Accessed October 18, 2016).
- 26 Journal of Manipulative and Physiological Therapeutics 1999 Oct;22(8):530-3
- What You Need to Know About Vaccine Effectiveness and Alternatives