year. Outbreaks occurred in colleges and hospitals, in some places the disease attacking upwards of 40% of their populations. Reports of absenteeism among students and nurses grew. Schools in Los Angeles, for example, reported rates ranging from 10 to 25%, compared to a typical 5 or 6%. The Greater New York Hospital Association reported absenteeism of 15 to 20% among staff and urged its members to impose visitor restrictions to safeguard patients. Institutions in many states dismissed their students early for the holidays. In New York and many other areas, holiday sales suffered mid-December, which affected retailers blamed on the flu epidemic (though inflation could have contributed to this as well). Economic activity was also hampered by high levels of industrial absenteeism. On 18 December, it was reported that President Johnson had been hospitalized at Bethesda Naval Hospital with flu-like symptoms, but whether the new variant was the cause of his illness was not made clear. He returned to the White House on 22 December. Vice President Humphrey was also reported to be ailing from the flu on the day Johnson's condition was revealed. Flu-like illness kept other senior governmental officials from their posts around this time, such as National Security Advisor Walt Rostow, Deputy White House Press Secretary Tom Johnson, and chairman of the Joint Chiefs of Staff General Earle Wheeler. On 23 December, it was reported that President-elect Nixon had been ill with the flu at his daughter's wedding the day before. Nixon later claimed that "the wedding cured the flu." Peak influenza activity for most states most likely occurred in the latter half of December or early January, but the exact week was impossible to determine due to the holiday season. Activity declined throughout January. Excess pneumonia-influenza mortality passed the epidemic threshold during the first week of December and increased rapidly over the next month, peaking in the first half of January. It took until late March for mortality to return to normal levels. There was no second wave during this season. Following the epidemic of influenza A, outbreaks of influenza B began in late January and continued until late March. Mostly elementary-school children were affected. This influenza B activity fit within the pattern of epidemics every three to six years, but the 1968–1969 flu season became the first documented instance of two major influenza A epidemics to occur in successive seasons. Given the widespread epidemic levels