Aug 6 (Reuters) - Money flows into U.S. bond funds jumped in the week to Aug. 4, as investors rushed towards safety on fears over the rapid spread of the Delta variant of COVID-19 and slowing manufacturing activity. Data from Refinitiv Lipper showed U.S. bond funds attracted a net $6.66 billion, the most in four weeks. U.S. government and municipal debt funds received $3.4 billion, the most in 10 months. Data released during the week showed U.S. manufacturing growth slowed for the second straight month in July, while, U.S. private payrolls increased less than expected. read more Optimism over U.S. companies" second-quarter earnings boosted stock prices during the week, however, lingering virus concerns capped the inflows. U.S. equity funds received just $470 million, a 94% drop compared with the previous week. Overall, earnings at S&P 500 firms are estimated to have climbed about 90% in the second quarter compared with forecasts of 65.4% at the start of July, according to IBES data from Refinitiv. Among sectors, tech funds received a net $1.3 billion, about 37% more compared with the previous week. Financial sector funds, however, witnessed outflows worth $673 million.