One drawback of the seasonal flu vaccine is that it's made with egg proteins – a possible problem for people with egg allergies. But next year, they will have a new egg-free option.
The US Food and Drug Administration has just approved the first flu shot made without eggs or the influenza virus itself.
The vaccine is called Flublok. It protects against three strains of the flu for adults aged 18 to 49.
Flublok is manufactured by Protein Science Corporation in Meriden, Conn., using an insect virus called baculovirus and an influenza protein called hemagglutinin (HA).
HA is the protein in flu viruses that lets the virus actually enter the body's cells. Therefore, human immune system antibodies – the cells that fight disease – specifically go after HA.
HA is included in the production of all flu shots so that the body will develop antibodies against HA in case the real flu comes along.
Having the HA and the inactivated insect virus are sufficient to spur the body create antibodies, making it unnecessary to include the full inactivated flu virus in the vaccine.
Flublok protects against two strains of influenza A (H1N1 and H3N2) and one strain of influenza B. A study in which 2,300 people received Flublok showed it was approximately 44.6 percent effective in protecting them against all circulating flu strains, including those not included in the shot.
That group which received Flublok had been compared to a group of a similar number who had received a placebo (fake shot) for the study.
The study showing Flublok's safety involved about 2,500 people who received the vaccine. The most common side effects those people reported were soreness where they got the shot, headache, fatigue and muscle aches. These are similar side effects to the ones seen in other flu shots.
Flublok lasts for 16 weeks from the day it's made. There are several advantages to a flu shot without egg proteins or the influenza virus.
First, people with egg allergies can receive this shot without being concerned about an allergic reaction.
Second, the shot can be manufactured more quickly during a pandemic without concerns about a shortage of eggs or flu viruses.