Estimated effectiveness was 68% against influenza B and 32% against type A.
The combined vaccine elicited higher immune response against SARS-CoV-2.
The Wall Street Journal reports the Trump administration is investing $500 million in the universal vaccine project.
Only 5% of women experienced a change in cycle length of at least 8 days.
The rate of Black adults receiving seasonal flu shots increased 7 percentage points.
Protection, however, dropped from 40% to 18% after 120 or more days.
Two lawmakers raise concerns about future scientific credibility and the availability of vaccines.
The rate also increased with each additional underlying medical condition.
The death-rate ratio of adults aged 70 years and older and children younger than 5 years climbed globally, with the Western Pacific Region experiencing the largest increase.
Like the recent WHO recommendation, the picks change the H3N2 strain for egg- and cell-based vaccines.