It is the tail end of the winter season and time to take stock of the Pneumonias seen in the past few months. As tertiary care physicians, we only see the tip of the iceberg. All mild clinical and subclinical cases that sweep the community will contribute to both herd immunity and the virulence of the organism for the next season.
The presently circulating strains are Influenza A (H1N1)2009, Circulating seasonal Influenza A (H3N2) and Influenza B. The incubation period is 1-2 days. Infectivity continues even after the onset of infection. Peak viral shedding occurs on day 1 of symptoms.
While declaring the Pandemic to be over in August 2010, World Health Organization conveyed that Pandemic Influenza A (HINI) virus that caused Pandemic [2009-2010] would circulate as Seasonal Influenza virus for some time. World Health Organization recommends vaccination of high-risk groups with Seasonal Influenza Vaccine. Vaccination prevents severe outcomes caused by influenza viruses. The vaccine advice has been divided into two groups. It is recommended for those with comorbid conditions and pregnant women (irrespective of the stage of pregnancy). It is desirable in the elderly (>65yrs) and children between 6 months to 8 years. The currently available vaccine (Northern hemisphere trivalent vaccine for the winter of 2016-17) may be used until May 2017. These vaccines have a 70-80% effectiveness and take 3 weeks to give immunity.
Also Read: Why are vaccines for pneumonia important for elderly?
The infection is spread by droplets and contact with fomites. It affects mostly urban and peri-urban areas due to overcrowding. As expected the incidence and an aggressive course is higher in young children and those above 65 years with comorbid conditions.
Our clinical experience is in line with what is described in the literature. Fever is of a shorter duration and breathlessness is the main symptom. Hypoxia is the key sign. Radiologically the consolidation is far denser but the morbidity and mortality is lower than in the last three years.
It is essential that the Influenza type is determined by appropriate clinical sampling. The indiscriminate use of antiflu medication may cause viral resistance. On the other hand, a negative test because of inappropriate sampling may lead to improper treatment.
While the newspapers shout out a higher mortality actual figures from the Department of health are still awaited and should be more informative. The cost of sampling in milder cases is prohibitive and so we are unlikely to know the complete impact.
Rest assured that we have had a reasonably good season with limited mortality.
Article by Dr. Supriya Sundaram, FRCP(LONDON), FRCP(EDIN)
Consultant Chest Physician & Intensivist, Kauvery Hospital