Regardless of the type of vaccine administered, “it’s probable that the older you are, the less likely you are to have a robust response to vaccination,” DeMaria said.
Beyond immunizations, washing hands frequently with soap and water, keeping your hands away from your eyes, nose and mouth, and avoiding close contact with sick people can also help prevent flu infections, according to the CDC.
Getting an accurate accounting of how many Americans develop the flu each year is nearly impossible because most people with symptoms never visit the doctor.
“It’s hard to know entirely for sure whether you have the flu or a bad cold,” said Dr. Joshua Kosowsky, vice chair and clinical director of Brigham and Women’s Hospital’s emergency department and coauthor of “When Doctors Don’t Listen.” “If you have fever, body aches, and fatigue along with a cough during flu season, it’s likely you also have the flu.”
More than 35 percent of patients in the New England region who went to see doctors with flu-like symptoms tested positive for influenza during late December, according to the CDC, and most flu patients are instructed to return home and manage their symptoms with bed rest, plenty of fluids, and ibuprofen or acetaminophen to reduce body aches and fever.
What usually leads people to seek medical attention, Kosowsky said, are severe symptoms such as chest pain — which could indicate pneumonia — shortness of breath, or dizziness due to dehydration. Some may also be looking for a prescription for an antiviral drug such as Tamiflu, which work best when given within the first day or two of symptoms appearing.
Boston resident Stephanie Allen, 40, said she was compelled to drag herself to her doctor’s office a day after Christmas after more than two days of fever, chills, vomiting, and a hacking cough. “I almost wasn’t going to go, but then a friend told me about Tamiflu,” said Allen, who hadn’t received a flu immunization and who tested positive for the flu virus. But she might not have received Tamiflu early enough to help: A week later, she was still dealing with a cough, headache, and clogged sinuses.
None of the flu strains circulating this year has shown resistance to either of the antivirals on the market — Tamiflu (oseltamivir) and Relenza (zanamivir).
They’re also 70 to 90 percent effective at preventing the flu in those who are caring for infected individuals in their household.
“The drugs shorten the course of symptoms, on average, by about a day,” said Dr. Geneve Allison, an infectious disease physician at Tufts Medical Center. “But they could shorten symptoms by up to three days if you take the drug within the first 24 hours after the onset of symptoms.” Tamiflu was approved last month for use in babies as young as 2 weeks.
Whether the antiviral drugs reduce severe flu complications that lead to hospitalizations or serious bacterial infections such as pneumonia depends on whom you ask. The US Food and Drug Administration states on its website that neither Tamiflu nor Relenza has been shown to prevent complications such as pneumonia based on clinical trial data provided to the agency from manufacturers.
The CDC, on the other hand, states on its website that “early antiviral treatment . . . may reduce the risk of complications from influenza (e.g., otitis media in young children, pneumonia, respiratory failure) and death, and shorten the duration of hospitalization.” That’s based on studying patients in hospitals who have been treated with the drug, according to Tim Uyeki, chief medical officer in the influenza division at the CDC.
Researchers have been pressing Roche, manufacturer of Tamiflu, to release its full set of clinical trial data to get a better handle on the drug’s benefits and possible psychiatric side effects such as delirium, hallucinations, and self-injury. The FDA has the full data but says it’s not required to release it to the public; the CDC doesn’t have the data.
“Eight out of the 10 trials on which Roche bases it claims for safety and effectiveness have never been published,” said Peter Doshi, a postdoctoral fellow at the Johns Hopkins University School of Medicine in Baltimore who has been leading the effort to review the Tamiflu data. “There’s a whole world of hidden data, and it’s just not acceptable.”
Roche responded in a statement that it is planning to set up an advisory board of experts from outside the pharmaceutical industry “to review the totality of Tamiflu data and agree on a statistical analysis plan. We believe this approach is a fair and transparent way of addressing this public debate.”