A government shutdown in the middle of one of the deadliest flu seasons on record could hinder efforts to treat and monitor the disease before it claims more lives.

The Centers for Disease and Control Prevention deliver weekly influenza reports and distribute the flu vaccination. Thirty children have already died from the flu so far this season, the CDC reported, and there’s still two months left. The vaccine was 48 percent effective during the 2015-2016 season and 39 percent effective during the 2016-2017 season, according to the CDC.

Sixty-three percent of CDC employees were furloughed on Monday due to the shutdown. Despite the absence of more than half of the agency, CDC spokeswoman Kathy Harben told The Washington Post on Friday that the organization would continue to respond to “urgent disease outbreaks” and monitor flu cases across the country.

But a former CDC leader speculated that a long shutdown could slow down the agency’s effectiveness at helping patients. “Doctors in different areas would be less prepared to provide rapid treatment,” former agency director Tom Frieden told NPR on Sunday.

This year’s vaccinations have been less effective than before. This season’s flu shot contains strains of influenza B, H1N1, and H3N2, but the latter is less effective than it was hoped, as  The Daily Beast previously reported.

The result has been severe from coast to coast. In Maine, 21 people have died from the flu, according to an AP report. In California, 42 people have already died from influenza, the Los Angeles Times reported. Thousands have flocked to hospitals in California for flu relief; a Loma Linda hospital set up emergency tents to treat the sick.

The government shutdown is poised to end after Democrats agreed with Republicans to fund . the government through February 8. Though this shutdown only lasted a weekend, a longer shutdown could harm the CDC’s measures to prevent the flu at the season’s peak, which is usually in February.

Though the shutdown ended Monday, the flu season is gearing up to be worse than previous ones. According to the Centers for Disease Control and Prevention, recent flu season have peaked later in the year. The 2015-2016 season peaked in March and 85 kids died from the flu during that season. (The CDC does not record how many adults die from influenza.)  Last year’s season peaked in February, a common month, with 101 children flu-related deaths. But the 2017-2018 flu has already took 30 children’s lives.   

What makes this year so deadly may be the ineffectiveness of the vaccination. This year’s flu shot contains strains of influenza B, H1N1, and H3N2, but the latter is less effective than it was hoped, according to a January report in The Daily Beast.

The CDC monitors influenza cases across the country, and controls the distribution of vaccinations. Employees from non-essential departments stayed home on Monday. Sixty-three percent of employees at the Centers for Disease Control and Prevention were furloughed as a result, the Washington Post reported Monday.

The CDC’s recent weekly report revealed that 10 children have died from influenza since the second week of January.

Fatal influenza cases have impacted both coasts. In Maine, 21 people have died from the flu, according to an AP report. In California, 42 people have already died from influenza since the season began in October, according to a Los Angeles Times report. Thousands have flocked to hospitals in California for flu relief; a Loma Linda hospital set up emergency tents to treat the sick.