These requirements occasionally engender union lawsuits on narrow collective bargaining grounds, but proponents note that courts have generally endorsed forced vaccination laws affecting the general population during disease outbreaks.Vaccination against influenza is especially considered important for members of high-risk groups who would be likely to have complications from influenza, for example pregnant women and children and teenagers from six months to 18 years of age who are receiving aspirin- or salicylate-containing medications and who might be at risk for experiencing Reye syndrome after influenza virus infection;
In raising the upper age limit to 18 years, the aim is to reduce both the time children and parents lose from visits to pediatricians and missing school and the need for antibiotics for complications
An added benefit expected from the vaccination of children is a reduction in the number of influenza cases among parents and other household members, and of possible spread to the general community.The CDC indicated that live attenuated influenza vaccine (LAIV), also called the nasal spray vaccine, was not recommended for the 2016–2017 flu season in the United States.Furthermore, the CDC recommends that health care personnel who care for severely immunocompromised persons receive injections (TIV or QIV) rather than LAIV. United Kingdom
Dr Jenny Harries maintained winter 2021–2022 in the UK will be "uncertain" since flu and COVID-19 will be circulating together for the first time. She urged eligible people to get COVID-19 and flu vaccines. She maintains flu vaccination is important every year.
European UnionThe composition of virus vaccines for use in the European Union for the 2020–2021 Northern Hemisphere influenza season recommended by the European Medicines Agency on April 1, 2020, was:Egg-based or live attenuated trivalent vaccines should contain:
an A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus;
an A/Hong Kong/2671/2019 (H3N2)-like virus;
a B/Washington/02/2019 (B/Victoria lineage)-like virus.Cell-based trivalent vaccines should contain:
an A/Hawaii/70/2019 (H1N1)pdm09-like virus;
an A/Hong Kong/45/2019 (H3N2)-like virus;
a B/Washington/02/2019 (B/Victoria lineage)-like virus.A B/Phuket/3073/2013-like virus is recommended in addition to the strains mentioned above for the quadrivalent vaccines. 2021 southern hemisphere
The composition of vaccines for use in the 2021 Southern Hemisphere influenza season influenza season recommended by the World Health Organization in September 2020:For egg-based (trivalent):

an A/Victoria/2570/2019 (H1N1)pdm09-like virus;
an A/Hong Kong/2671/2019 (H3N2)-like virus; and
a B/Washington/02/2019 (B/Victoria lineage)-like virus.For cell- or recombinant-based (trivalent):

an A/Wisconsin/588/2019 (H1N1)pdm09-like virus;
an A/Hong Kong/45/2019 (H3N2)-like virus; and
a B/Washington/02/2019 (B/Victoria lineage)-like virus.The quadrivalent version should contain, in addition to the above:

a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.In Australia, the standard vaccine under the National Immunisation Program for 2021 is the quadrivalent one. 2021–2022 northern hemisphere
The composition of virus vaccines for use in the 2021–2022 Northern Hemisphere influenza season is

European UnionThe composition of virus vaccines for use in the European Union for the 2021–2022 Northern Hemisphere influenza season recommended by the European Medicines Agency on March 30, 2021, is:Egg-based or live attenuated trivalent vaccines should contain:
an A/Victoria/2570/2019 (H1N1)pdm09-like virus;
an A/Cambodia/e0826360/2020 (H3N2)-like virus;
a B/Washington/02/2019 (B/Victoria lineage)-like virus.Cell-based trivalent vaccines should contain:
an A/Wisconsin/588/2019 (H1N1)pdm09-like virus;
an A/Cambodia/e0826360/2020 (H3N2)-like virus;
a B/Washington/02/2019 (B/Victoria lineage)-like virus.A B/Phuket/3073/2013-like virus is recommended in addition to the strains mentioned above for the quadrivalent vaccines.