Illumina, Inc. ILMN recently announced preliminary revenues for first-quarter 2021. The company expects to release detailed financial results for the period on Apr 27.As per the preliminary report, first-quarter 2021 revenues are estimated to be approximately $1,085 million, up 26% from the year-ago quarter’s $859 million. The Zacks Consensus Estimate of $928.2 million remains below the preliminary figure.As per the company, the sales uptick in the first quarter resulted from a surge in orders amounting to around $1.4 billion and year-over-year projected sequencing revenue growth of approximately 28%. Sequencing consumables business is expected to have grown by approximately 25% compared to the year-ago figures. Further, the preliminary estimate of COVID-19 surveillance revenues for sequencing consumables is approximately $20 million for the quarter.Sequencing instrument business is expected to have registered growth of approximately 120% year over year, thus reflecting strength across all instrument categories.Illumina now expects full-year 2021 revenue growth in the band of 25-28%, banking on the strength in its performance over the past few months. This is significantly up from its earlier projection of 17-20% announced in February. The Zacks Consensus Estimate for the full-year revenues is currently pegged at $3.89 billion.Following this after-market release yesterday, shares of the company are up 10.1% in today’s premarket trading.A Brief Q1 AnalysisIllumina, during the first quarter, observed a robust improvement in its Sequencing consumables arm compared to the pandemic phase, thus demonstrating strength in its core business. The company is upbeat about its performance in the to-be-reported quarter as the majority of its customers are now operating at pre-COVID-19 levels. Strength in its order receipts is also buoying optimism.The company also confirmed in its preliminary results that its mid-throughput category recorded another solid quarter for placements. Per Illumina, some of its customers built additional capacity for COVID-19 surveillance work and accelerated instrument purchases. This resulted in approximately $35 million of incremental instrument revenues in the quarter.Management also confirmed witnessing broad-based acceleration across Illumina’s core clinical and research applications with the increased adoption of next-generation sequencing (“NGS”). Additionally, the company recorded increased demand for COVID-19 surveillance, worldwide, due to the critical role that Illumina’s NGS technology plays to combat the pandemic.Meanwhile, the company’s preliminary projection of a robust improvement in revenues compared to the sequentially last-reported quarter lifts our confidence.Price PerformanceShares of the company have gained 0.6% in the past three months versus the industry’s 8.1% fall and the S&P 500’s 7.7% rise.Zacks Rank & Key PicksCurrently, Illumina carries a Zacks Rank #3 (Hold).Some better-ranked stocks from the broader medical space are Hologic, Inc. HOLX, Hill-Rom Holdings, Inc. HRC and DENTSPLY SIRONA Inc. XRAY.Hologic’s long-term earnings growth rate is estimated at 15.4%. The company presently sports a Zacks Rank #2 (Buy). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.Hill-Rom’s long-term earnings growth rate is estimated at 7.3%. It currently carries a Zacks Rank #2.DENTSPLY’s long-term earnings growth rate is estimated at 20%. The company presently carries a Zacks Rank #2.Zacks Top 10 Stocks for 2021In addition to the stocks discussed above, would you like to know about our 10 best buy-and-hold tickers for the entirety of 2021?Last year's 2020 Zacks Top 10 Stocks portfolio returned gains as high as +386.8%. Now a brand-new portfolio has been handpicked from over 4,000 companies covered by the Zacks Rank. Don’t miss your chance to get in on these long-term buys.Access Zacks Top 10 Stocks for 2021 today >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Illumina, Inc. (ILMN): Free Stock Analysis Report DENTSPLY SIRONA Inc. (XRAY): Free Stock Analysis Report Hologic, Inc. (HOLX): Free Stock Analysis Report HillRom Holdings, Inc. (HRC): Free Stock Analysis Report To read this article on Zacks.com click here.