Influenza is one of the world’s most devastating vaccine-preventable diseases, which makes staying ahead of the disease with leading-edge immunology science even more crucial.
“Though it’s hard to make projections on the upcoming flu season based on a prior season,” explains Dan DiVito, senior director influenza vaccines for Sanofi Pasteur U.S., “we look closely at activity in the Southern Hemisphere because its winter season—and its flu—hits during our summer. Their activity is usually pretty predictive of ours. In countries such as Australia and South Africa, the influenza strains were less severe as the prior year, but that doesn’t always predict exactly what will happen here.”
By the end of the 2017 flu season, which usually starts in October and peaks between December and February, the Centers for Disease Control and Prevention (CDC) reported a vaccine effectiveness of about 40 percent.
“We’d like that number to be better, but it’s typical,” DiVito says. “The entire vaccine enterprise needs to get better at communicating how important intervention is. The flu can be so severe that a 40 percent effective vaccine can have tremendous public health impact.”
According to the CDC, flu vaccination prevented an estimated 85,000 flu-related hospitalizations during the 2016–2017 flu season. A 2018 study indicated that from 2012–2015, flu vaccinations reduced the risk of adult flu-related ICU admissions by 82 percent.
Data has shown the adverse impact that influenza has on the management of chronic disease. According to the CDC, flu vaccination has been linked to lower rates of some cardiac events among people with heart disease. It has also has been shown to be associated with reduced hospitalizations among people with diabetes and chronic lung disease.
“To fully manage chronic conditions such as cardiovascular disease and diabetes you also have to keep influenza out of the picture,” DiVito says.
An Evolving Science
Sanofi Pasteur manufactures Fluzone High-Dose and Flublok Quadrivalent, injectable vaccines made to protect against the flu viruses that are predicted as the most likely to cause illness for a particular flu season. Fluzone High-Dose vaccine contains four times the amount of antigen contained in regular flu shots, which offers better protection from influenza for adults age 65 and older. The Flublok Quadrivalent vaccine is the first vaccine proven to prevent more flu than the standard quadrivalent influenza vaccine for adults age 50 and older.
The manufacturing processes for vaccines can differ, potentially influencing efficacy of the products, DiVito explains. The most traditional way to make an influenza vaccine involves growing the virus first in some other medium, such as in a chicken egg or a mammal cell. With this process, the virus has to be changed in order for it to grow at the speed and scale needed to manufacture vaccines.
However, the recombinant manufacturing process, which is how Flublok Quadrivalent is made, is quite different. The virus does not have to be grown with the traditional process. Instead, the genetic code for the protein that’s chosen for the vaccine is copied and mass-produced, making the vaccine an exact genetic match for the flu virus.
“The technology is exciting, but the positive clinical results are even more interesting,” DiVito says. “In a 2017 study published in the New England Journal of Medicine, Flublok Quadrivalent provided 30 to 43 percent better protection against the influenza disease in adults 50 and older versus a standard quadrivalent flu vaccine.”
Sanofi and other vaccine manufacturers, biotechnology companies and government organizations are working on what’s classically called a universal vaccine, but more accurately called a “broadly protective” vaccine.
DiVito explains, “The term ‘universal’ makes people think it’s a one-time shot for all flu viruses, but that may never come. But the idea of creating a vaccine that prevents more strains or lasts more than one season is probably within reach, and we are progressing toward that. It won’t be next season or three seasons from now—we’re talking in the more distant future. In the near-term, we’re also focused on expanding use of the improved vaccines we already have.”
Manufacturers are feeling pressure to deliver vaccines much earlier each year, with pharmacies, physicians and hospitals eager for them as soon as shipments can be delivered. “We have healthcare providers who want 100 percent of their flu vaccines on August 5th. But when we look at the timing of the actual immunization, it’s not getting much earlier—providers typically don’t start immunizing until after Labor Day, peak in October, and probably won’t finish immunizing until March. They want to have it in their refrigerator for seven months rather than it be in ours.”
DiVito sees the decision to warehouse vaccines as evolving from shortages that occurred years ago. “That fear of having a patient show up for an immunization and it not being in the refrigerator drives providers to store a surplus of the product,” he notes.
To build customers’ trust, Sanofi Pasteur is inviting them to schedule shipments throughout the influenza season. “Healthcare organizations can order vaccines a week at a time so they don’t have to worry about getting stuck with excess inventory,” DiVito says. “Even if the product is on our shelves instead of theirs, the customer can trust that it will be there. This will allow providers to order it in a more rational fashion like they order other vaccines and products.”
Although the stockpiling is unsettling, DiVito is more concerned about the slowdown of orders in November and December. “We see a dramatic tail off in immunizations around Thanksgiving, even though the typical peak of disease is in January and February,” he says. “Nearly 200 million Americans go unvaccinated every year. There are additional months they could be vaccinated.”