During the past few decades, the number of companies producing vaccines has dwindled to just a handful. There are other players in the space, but today, the four big drug companies that now dominate the market are Merck, Pfizer, Sanofi Pasteur and GlaxoSmithKline.

Selling a vaccine like Shingrix for the shingles or Gardasil 9 for HPV is where a company can make big profits. Gardasil 9 reached over $3 billion in sales in 2018 and with the patent not expiring until 2028 in the U.S., it could reach billions more, according to analysts.

Watch this video to find out what the future holds for vaccines makers Merck, Pfizer, Sanofi Pasteur and GlaxoSmithKline.

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