The strong immune reactions of young adults were postulated to have ravaged the body, whereas the weaker immune reactions of children and middle-aged adults resulted in fewer deaths among those groups. Because the virus that caused the disease was too small to be seen under a microscope at the time, there were problems with correctly diagnosing it. The bacterium haemophilus influenzae was instead mistakenly thought to be the cause, as it was big enough to be seen and was present in many, though not all, patients. During the deadly second wave there were also fears that it was in fact plague, dengue fever, or cholera. Another common misdiagnosis was typhus, which was common in circumstances of social upheaval, and was therefore also affecting Russia in the aftermath of the October Revolution. In Chile, the view of the country's elite was that the nation was in severe decline, and therefore the assumption of doctors was that the disease was typhus caused by poor hygiene, and not an infectious one, causing a mismanaged response which did not ban mass gatherings. While systems for alerting public health authorities of infectious spread did exist in 1918, they did not generally include influenza, leading to a delayed response. Nevertheless, actions were taken. Maritime quarantines were declared on islands such as Iceland, Australia, and American Samoa, saving many lives. Social distancing measures were introduced, for example closing schools, theatres, and places of worship, limiting public transportation, and banning mass gatherings. Wearing face masks became common in some places, such as Japan, though there were debates over their efficacy. There was also some resistance to their use, as exemplified by the Anti-Mask League of San Francisco. Vaccines were also developed, but as these were based on bacteria and not the actual virus, they could only help with secondary infections. The actual enforcement of various restrictions varied. A later study found that measures such as banning mass gatherings and requiring the wearing of face masks could cut the death rate up to 50 percent, but this was dependent on them being imposed early in the outbreak and not being lifted prematurely. As there were no antiviral drugs to treat the virus, and no antibiotics to treat the secondary bacterial infections, doctors would rely on a random assortment of medicines with varying degrees of effectiveness, such as aspirin, quinine, arsenics, digitalis, strychnine, epsom salts, castor oil, and iodine. Treatments of traditional medicine, such as bloodletting, ayurveda, and kampo were also applied.