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COVID‐19 disease has plagued the world economy and affected the overall well‐being and life of most of the people. Natural infection as well as vaccination leads to the development of an immune response against the pathogen. This involves the production of antibodies, which can neutralize the virus during future challenges. In addition, the development of cellular immune memory with memory B and T cells provides long‐lasting protection. The longevity of the immune response has been a subject of intensive research in this field. The extent of immunity conferred by different forms of vaccination or natural infections remained debatable for long. Hence, understanding the effectiveness of these responses among different groups of people can assist government organizations in making informed policy decisions. In this article, based on the publicly available data, we have reviewed the memory response generated by some of the vaccines against SARS‐CoV‐2 and its variants, particularly B cell memory in different groups of individuals. [ABSTRACT FROM AUTHOR]

The formation of rhamnolipid complexes with metal ions of chromium (VI) and lead (II) has been studied spectrophotometrically, conductometrically, and by surface tension measurement. The values of the critical micelle concentration (CMC) of rhamnolipid, obtained by spectroscopic, conductometric, and surface tension measurements, were 5.2 × 105, 5.0 × 105, and 5.3 × 105 mol.dm−3, respectively, which are in close agreement. An increase in CMC on increasing metal ion content in the rhamnolipid solution and a shift in λmax in the spectra of rhamnolipid indicated the formation of a complex between rhamnolipid and both the metal ions, namely, chromium (VI) and lead (II). The values of stability constants for the {rhamnolipid–chromium (VI)} and {rhamnolipid–lead (II)} complexes have been determined by spectroscopic data and were as 0.58 × 104 and 0.50 × 104 at 308 K, respectively. The thermodynamic parameters for micellization, namely, free energy change (∆Gmic), entropy change (∆Smic), and heat enthalpy change (∆Hmic), have been determined by conductivity measurements. An increase in the negative value of ∆Gmic and a decrease in the value of ∆Smicon increasing metal ion content in the surfactant solution indicated lower micellization of rhamnolipid in the presence of metal ions. The electrostatic attractions and entrapment of chromium (VI) in the micelles of the biosurfactants were found to be responsible for {rhamnolipid–lead (II)} and {rhamnolipid–chromium (VI)} complexes, respectively. [ABSTRACT FROM AUTHOR]