This could be particularly nasty flu season, experts predict

There’s a 30% chance season will peak around the end of December and a 60% chance in late January.

  • Lena H. Sun The Washington Post
  • Friday, December 22, 2017 8:35pm
  • Nation-World

The Washington Post

This flu season could be a potentially harsh one, and experts say the worst time could coincide with the height of the holiday season and start of the new year.

“Flu is picking up and picking up early,” said Daniel Jernigan, director of the influenza division at the Centers for Disease Control and Prevention. “A lot of people are getting together in the next few days and weeks. All of those folks who are traveling, some of them will be traveling with their influenza.”

CDC’s latest weekly influenza data, released Friday, shows more than 13,400 confirmed cases in the U.S. as of last Saturday. Widespread flu activity has been reported in 23 states.

CDC’s flu forecasters say there’s a 30 percent chance the season will peak around the end of December and a 60 percent chance that the greatest incidence will be by late January, Jernigan said. Generally, flu season peaks near the end of February.

The earlier start this fall, as well as the increasing activity in many parts of the country, “could indicate that this is going to be a more severe season than usual,” said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

Health officials are urging people to get protected, especially if they’re going to be around young children and the elderly, groups who are most at risk. “If you’re getting ready to see grandmother, call before you go — and make sure you’ve gotten your flu vaccine,” Jernigan said.

The CDC recommends an injectable flu vaccine for everyone 6 months or older as soon as possible. The body takes about two weeks to produce a full immune response.

The other sign that this flu season could be a more serious one: The predominant strain is also the nastiest, H3N2, which causes the worst outbreaks of the two influenza A viruses and two types of influenza B viruses that circulate among people. Seasons where H3N2 dominates typically result in the most complications, especially for the very young, the elderly and people with certain chronic health conditions, experts say.

“Of the viruses we hate, we hate H3N2 more than the other ones,” Jernigan said.

This strain, which has been around for 50 years, is able to change more quickly to get around the human body’s immune system than the other viruses targeted in this year’s seasonal flu vaccine. H3N2 was the predominant strain three years ago, when the flu season was particularly nasty. “Most of the indicators are showing a pretty substantial rise that may be signaling an early season along the lines of 2014-2015,” Jernigan said.

Even in a good year, the flu vaccine isn’t as good as most other vaccines. Health officials must choose the influenza strains that vaccine makers should target for an upcoming season months in advance, when it is hard to know what strains might be circulating.

When flu vaccines are well matched to circulating viruses, effectiveness is, at best, around 60 percent. (Measles vaccine, by comparison, is about 97 percent effective with two doses.) In a year when the circulating flu strains closely match the vaccine, that effectiveness rate means that about 3 out of 5 people who get shots are far less likely to become so sick that they require a visit to a doctor.

For older adults, vaccination not only reduces the chances they will get infected but helps keep them out of the hospital by reducing the severity of infection and related complications, experts say.

A study in Pediatrics this year was the first of its kind to show that vaccination lowered the risk of flu-associated death by half among children with underlying high-risk medical conditions and by nearly two-thirds among healthy children.

Data collected by the CDC this fall show the majority of viruses collected in the U.S. to be similar to the viruses used to grow the current vaccine.

Flu vaccines are killed or highly weakened viruses that trigger the body’s immune system to produce antibodies to protect against the real virus. Most U.S. flu vaccines are produced using egg-based technology.

Scientists have long known that viruses also change in these egg hosts, but recent research suggests that the way flu shots are made may be making them less effective, especially for H3N2.

“When that (H3N2) virus was put into eggs, we see some very tiny changes that make the egg-grown virus look less similar to the viruses that are circulating now,” which could affect the vaccine’s effectiveness, Jernigan said.

Officials have been especially concerned about H3N2 this year based on surveillance in the Southern Hemisphere — often a clue for what to expect in the U.S. — because of record-high numbers of laboratory-confirmed cases of influenza there and higher-than-average numbers of hospitalizations and deaths.

Flu virus infections began increasing earlier than usual in Australia and hit historic highs in some areas, according to government data. H3N2 viruses were most common in that country, and interim reports suggest vaccine effectiveness against H3N2 was only 10 percent. The vaccine for the U.S. has the same composition as the one used in the Southern Hemisphere.

But Australia vaccinates only the elderly and infirm, who generally don’t respond as well to vaccines. Its approach makes a difference in vaccine effectiveness rates since children have better responses. “It is impossible to say that (the United States) will have a similar 10 percent efficacy against H3N2 with the current vaccine, similar to Australia,” Fauci said.

CDC officials said a better predictor of vaccine effectiveness for H3N2 is last season’s vaccine’s effectiveness in the U.S. The current vaccine contains the same H3N2 component as last season, which was about 32 percent effective. Most circulating H3N2 viruses that have been tested in the U.S. this fall are still similar to that H3N2 vaccine virus.

Since 2010, the flu has led to hundreds of thousands of hospitalizations and from 12,000 to 56,000 deaths annually in the U.S., CDC estimates.

Even though flu vaccine is not perfect, and some people who get vaccinated may still get flu, experts say data suggest that vaccination may make illness milder.

Talk to us

> Give us your news tips.

> Send us a letter to the editor.

> More Herald contact information.

More in Nation-World

FILE - Britain's Queen Elizabeth II looks on during a visit to officially open the new building at Thames Hospice, Maidenhead, England July 15, 2022. Buckingham Palace says Queen Elizabeth II is under medical supervision as doctors are “concerned for Her Majesty’s health.” The announcement comes a day after the 96-year-old monarch canceled a meeting of her Privy Council and was told to rest. (Kirsty O'Connor/Pool Photo via AP, File)
Queen Elizabeth II dead at 96 after 70 years on the throne

Britain’s longest-reigning monarch and a rock of stability across much of a turbulent century died Thursday.

A woman reacts as she prepares to leave an area for relatives of the passengers aboard China Eastern's flight MU5735 at the Guangzhou Baiyun International Airport, Tuesday, March 22, 2022, in Guangzhou. No survivors have been found as rescuers on Tuesday searched the scattered wreckage of a China Eastern plane carrying 132 people that crashed a day earlier on a wooded mountainside in China's worst air disaster in more than a decade. (AP Photo/Ng Han Guan)
No survivors found in crash of Boeing 737 in China

What caused the plane to drop out of the sky shortly before it was to being its descent remained a mystery.

In this photo taken by mobile phone released by Xinhua News Agency, a piece of wreckage of the China Eastern's flight MU5735 are seen after it crashed on the mountain in Tengxian County, south China's Guangxi Zhuang Autonomous Region on Monday, March 21, 2022. A China Eastern Boeing 737-800 with 132 people on board crashed in a remote mountainous area of southern China on Monday, officials said, setting off a forest fire visible from space in the country's worst air disaster in nearly a decade. (Xinhua via AP)
Boeing 737 crashes in southern China with 132 aboard

More than 15 hours after communication was lost with the plane, there was still no word of survivors.

In this photo taken from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks to the nation in Kyiv, Ukraine, Sunday, Feb. 27, 2022. Street fighting broke out in Ukraine's second-largest city Sunday and Russian troops put increasing pressure on strategic ports in the country's south following a wave of attacks on airfields and fuel facilities elsewhere that appeared to mark a new phase of Russia's invasion. (Ukrainian Presidential Press Office via AP)
Ukraine wants EU membership, but accession often takes years

President Volodymyr Zelenskyy’s request has enthusiastic support from several member states.

FILE - Ukrainian servicemen walk by fragments of a downed aircraft,  in in Kyiv, Ukraine, Friday, Feb. 25, 2022. The International Criminal Court's prosecutor has put combatants and their commanders on notice that he is monitoring Russia's invasion of Ukraine and has jurisdiction to prosecute war crimes and crimes against humanity. But, at the same time, Prosecutor Karim Khan acknowledges that he cannot investigate the crime of aggression. (AP Photo/Oleksandr Ratushniak, File)
ICC prosecutor to open probe into war crimes in Ukraine

U.N. human rights chief Michelle Bachelet confirmed that 102 civilians have been killed.

FILE - Refugees fleeing conflict from neighboring Ukraine arrive to Zahony, Hungary, Sunday, Feb. 27, 2022. As hundreds of thousands of Ukrainians seek refuge in neighboring countries, cradling children in one arm and clutching belongings in the other, leaders in Poland, Hungary, Bulgaria, Moldova and Romania are offering a hearty welcome. (AP Photo/Anna Szilagyi, File)
Europe welcomes Ukrainian refugees — others, less so

It is a stark difference from treatment given to migrants and refugees from the Middle East and Africa.

Afghan evacuees disembark the plane and board a bus after landing at Skopje International Airport, North Macedonia, on Wednesday, Sept. 15, 2021. North Macedonia has hosted another group of 44 Afghan evacuees on Wednesday where they will be sheltered temporarily till their transfer to final destinations. (AP Photo/Boris Grdanoski)
‘They are safe here.’ Snohomish County welcomes hundreds of Afghans

The county’s welcoming center has been a hub of services and assistance for migrants fleeing Afghanistan since October.

FILE - In this April 15, 2019, file photo, a vendor makes change for a marijuana customer at a cannabis marketplace in Los Angeles. An unwelcome trend is emerging in California, as the nation's most populous state enters its fifth year of broad legal marijuana sales. Industry experts say a growing number of license holders are secretly operating in the illegal market — working both sides of the economy to make ends meet. (AP Photo/Richard Vogel, File)
In California pot market, a hazy line between legal and not

Industry insiders say the practice of working simultaneously in the legal and illicit markets is a financial reality.

19 dead, including 9 children, in NYC apartment fire

More than five dozen people were injured and 13 people were still in critical condition in the hospital.

15 dead after Russian skydiver plane crashes

The L-410, a Czech-made twin-engine turboprop, crashed near the town of Menzelinsk.

FILE - In this March 29, 2018, file photo, the logo for Facebook appears on screens at the Nasdaq MarketSite in New York's Times Square. Facebook prematurely turned off safeguards designed to thwart misinformation and rabble rousing after Joe Biden defeated Donald Trump in the 2020 elections in a moneymaking move that a company whistleblower alleges contributed to the deadly Jan. 6, 2021, invasion of the U.S. Capitol. (AP Photo/Richard Drew, File)
Facebook, WhatsApp, Instagram in hourslong worldwide outage

Something made the social media giant’s routes inaccessable to the rest of the internet.

Oil washed up on Huntington Beach, Calif., on Sunday, Oct. 3, 2021. A major oil spill off the coast of Southern California fouled popular beaches and killed wildlife while crews scrambled Sunday to contain the crude before it spread further into protected wetlands. (AP Photo/Ringo H.W. Chiu)
Crews race to limited damage from California oil spill

At least 126,000 gallons (572,807 liters) of oil spilled into the waters off Orange County.

Support local journalism

If you value local news, make a gift now to support the trusted journalism you get in The Daily Herald. Donations processed in this system are not tax deductible.