The World Health Organization is recommending Chinese authorities expand their list of mandatory vaccinations.

WHO vaccination expert Lance Rodewald says kids in China should be given shots for influenza, pneumonia, meningitis and rotavirus.

"One of them that protects against bacteria—they cause meningitis and blood infections—called Thermopolis influenza, very serious disease. It's a category two vaccine. Many parents wisely select to have that vaccine for their child. But because that's not in the program, but parents can't afford to, so they can't get access to that vaccine. Another is rotavirus vaccine. WHO suggests all the countries should be rotavirus vaccine in their programs. This could protect against dehydrating, and that caused many hospitalizations of children. The fourth vaccine is influenza vaccine."

Meanwhile, the WHO is also calling for tighter regulations of privately sold vaccines in China.

This comes amid the ongoing vaccine scandal in China.

The scandal erupted earlier this month after two suspects were arrested in Shandong for selling black-market vaccines to hospitals.

Their arrest uncovered a ring of black-market vaccine sales across China, including the sale of improperly stored or expired vaccines in more than 20 provincial-level regions since 2011.

So far, more than 130 people have been detained in close to 70 different criminal cases connected to the scandal.