Scientists continue to work on better ways to design, conduct and evaluate non-randomized (., observational) studies to assess how well flu vaccines work. CDC has been working with researchers at universities and hospitals since the 2003-2004 flu season to estimate how well flu vaccine works through observational studies using laboratory-confirmed flu as the outcome. These studies currently use a very accurate and sensitive laboratory test known as RT-PCR (reverse transcription polymerase chain reaction) to confirm medically-attended flu virus infections as a specific outcome. CDC’s studies are conducted in five sites across the United States to gather more representative data. To assess how well the vaccine works across different age groups, CDC’s studies of flu vaccine effects have included all people aged 6 months and older recommended for an annual flu vaccination. Similar studies are being done in Australia, Canada and Europe. More recently, CDC has set up a second network the Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) that looks at how well flu vaccine protects against flu-related hospitalization among adults aged 18 and older.
With the high prevalence of heart disease , links between lifestyle factors, such as diet and physical activity, are undergoing extensive research. The original research into caffeine's role in this epidemic resulted in conflicting answers. Some evidence suggests an elevation in stress hormones from caffeine consumption that could pose a cardiovascular risk, but recent research has shown no relationship between caffeine ingestion and heart disease . In fact, studies have actually shown a protective effect against heart disease with habitual intake of caffeinated beverages in the elderly population. The reason for the discrepancy may be due to the kind of beverage being consumed. Studies have shown that coffee and tea were not associated with increases in blood pressure or arrhythmias, while soft drinks were. Research also showed that decaffeinated coffee and tea did not provide the same benefits as the caffeinated versions. The well-respected Framingham Heart Study examined all potential links between caffeine intake and cardiovascular disease and found no harmful effects from drinking coffee. There can, however, be exceptions to this. People react differently to caffeine, and some may experience elevations in blood pressure or arrhythmias. The blood pressure elevations are said to be short lived, lasting no more than several hours and are comparable to modest elevations experienced climbing a flight of stairs. It's always best to check with your physician if you are experiencing any side effects.