A few years ago, traveling in Jerusalem, I picked up a terrible souvenir: the flu. Rather than visiting important landmarks, I went sightseeing in the hospital emergency room. An important lesson came from that trip: always get a flu shot.

There are six options, some of them new this year:

  • Regular flu shot. This "trivalent" vaccine protects against the three strains of the virus that are expected to be most common and is recommended for everyone over the age of six months.

  • Quadrivalent flu shot. It This vaccine protects against the same three strains (an A/H1N1, A/H3N2, and a Type B) plus a fourth (another B).If you want really detailed information, click here.  It is recommended for everyone over the age of six months. This is the only shot that protects against four strains. There also  is a quadrivalent  nasal spray vaccine, the only nasal version this year. It  is recommended for people ages 2-49 – a smaller range than the shot – who are healthy and do not want to be stuck with a needle.

  • High dose flu shot. This contains a higher amount of the antigen (immune system stimulant) needed to create immunity. It is recommended for adults over 65 because the immune system weakens with age.

  • Intradermal (inside the skin) flu shot. This vaccine creates the same immune response but uses a much smaller needle.

  • Flublok flu shot. This is created without using chicken eggs and is suitable for adults aged 18-49 who are allergic to eggs. It protects against three types of flu.

  • Flucelvax flu shot. This vaccine is made using cultured animal cells, so it, too, is  appropriate for people egg allergies. If there is ever a flu pandemic, using cell cultures will allow  vaccines to be made more quickly.

Every once in a while – four times in the last century – the flu virus changes so dramatically that few people have the partial immunity that they developed from exposure to related strains in previous years. That's called a pandemic, as in the Type A H1N1 pandemic of 2009. Once a large percentage of the population developed immunity to that strain, through a combination of vaccination and infection, it no longer had pandemic potential, and its successors have been among the seasonal flu strains for the past few years.

Even the seasonal flu is serious, and we're fortunate to have a vaccine that can help keep us healthy. Do yourself (and everyone you know) a favor and get a flu shot. I will.

Teagan Keating is a second year master's student at Drexel's School of Public Health. Find her on Twitter.

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